Granddaughter pressed lots of buttons all at once. Now the washer on/off button constantly flashing and three of the buttons on the side - rinse hold, reduce crease, time saver - all flashing at same time! Pressing the cancel button does nothing at all. Help

I don't have a direct answer but here is a link to youtube videos regarding the Indesit washer.
Maybe there is something there that can help you.
ndesit Washing Machine WIL 123s YouTube

Did the unit have anything plugged into the blue two pin port? If so, trace that wire (black & gray) to the programming switch. Once you have located the switch, turn key on, press and release the button three times. The parking lights will flash once. Press the lock button on the new remote. Press and release the programming button once (two flashes), press unlock button. Press and release probramming button once( three flashes), press remote start button. Press and release programming button once (four flashes), press option button. Turn key off. test system.

The Service Manual for reference. Sears Parts Direct for reference.
I have tried to work with a few folks on this issue never received feed back to resolution see this post. I feel the issue is caused by one of three possible issues.

A stuck key issue/defective Spin Cycle key making constant contact forcing the Key/LED to cycle thru the Spin Cycle settings. Under normal conditions if you press and hold the Spin Select key it will cycle thru the settings, yours has a mind of its own (defective issue).

A false signal from the Control Board for the Spin Cycle.

A corrosion path issue at the Membrane Pad ribbon cable socket connection between pins 5 and 4. See page 20 of the SM button functionality “Spin” key.

Try to verify that the spin cycle membrane key is not stuck/defective signaling the Control Board to cycle thru the spin settings. I have not experienced this issue but let’s try the Membrane Pad Test to get a start point. See the Service Manual page 15, I have modified the process to make it a bit more understandable at least for me. Make sure the two digit display is not On or Lite.
Press the off button first so there is nothing displayed in the Two Digit display of your FAV6800AW.

Now Enter / Exit Service Mode

To enter Service Mode press the Enviro Plus and Spin Only keys for three seconds or until the control beeps. While in Service Mode, pressing the Presoak key will start a membrane switch check that verifies switch operation.

All the LEDs (except Presoak ) can be toggled or slewed by pressing the key associated with the LED or set of LEDs. Do not press the Presoak again during this test.

Press each key once and only once including the Signal Key the on side and the off side, also the UP and Down Arrow key of the LED display. All keys (including the OFF button) must be pressed within 5 minutes for this test to pass. “PA” will be displayed for five (5) seconds once all keys have been pressed and the test is completed (more like PA will be displayed for only a few seconds on my FAV6800AW). Following 10 seconds of inactivity at any point, this test will exit without any display. Let us know the results.

See my additional comment this board has message limit issues.

Try this and see if it works. Let me know.
Start your van. Then slide your temp lever all the way to the left (full cold). Then turn the Mode Control to 'panel' (the one that sends air to your face only). Then turn the 'blower switch' to all the way to full. Now go to the leftmost three buttons. Press the top one (rear wiper on constant) and the bottom one (rear wiper washer fluid). Hold these two for a few seconds. Once the lights come on solid then begin to flash you can let go. The AC will now calibrate. You will feel the air blow out of all the different zones at different intervals and see lights come on and go off. Then after a minute or two the top button you pressed will be slowly flashing. This means it has been completed . Press the last flashing button and you are done.

disconnect a/c compressor connector and reconnect make sure the connector is tight....my van was doing the same thing and after i did that it works great no more flashing lights

This error code means there is an abnormality.
If the on-off door lock LED on a Whirlpool washer flashes rapidly at the same time as at least one other LED, then this means there is an abnormality.
Try first to reset the machine. You can press and hold the reset button for a couple of seconds, otherwise turn off the power completely (unplug it) for 5 mins.

LD code is long drain one of 2 things the drain pump is frozen and need to be replaced or there is somthing in the pump. Pull the washer a way from the wall a bit and get a bunch of towels. Lean the washer back against the wall towards the middle in the back you will see the pump take it apart and find the clog.
it can be assessed through the bottom.

This error only shows in diagnostic mode, with power off choose any buttons except stop and power, press in intervals 5 seconds on and 5 seconds off until 88 appears and all light light up. If the user panel is faulted F 2 will flash in the display, press the same button you used to start diagnostics to jump to the next error code and once through 88 will flash and diagnostics will start. Sometimes once F2 flashes and the machine has not been repaired it will stick at that mode.

button selection : To select an option press the button and you will see a light come on above the button. Press again to cancel and the light will go out. You cannot alter the options once the machine is running. Note : remember to cancel buttons after use!

As you look at the machine
Left hand button... Rinse Hold.. use this option to Help reduce creasing of delicate or synthetic fabrics by holding clothes in the final rinse water. The rinse hold light will flash to indicate that the programme is holding final rinse water. Complete the final spin by pressing the Rinse Hold button when light is flashing.
This is not available with Wool or Spin only programmes.

Middle Button.... Energy Save... use this option to save money and time on lightly soiled loads. This is not available with the Quick Wash, Rinse and Spin, or Spin Only programmes.

Right Hand Button .... Super Rinse... use this option for Large Wash loads and items for young children or people with sensitive skin. This option increases the water level for the first two rinses. This is not available with Cold Wash, Rinse and Spin or Spin Only programmes.

Copied from my Hotpoint FEW12 user instruction sheet.
Hope it helps.

Sue

make sure none of the option buttons are stuck in if on is simply run a pin round the outer edge to release it