Why flash by 5 times the orange led?

Probably your waste ink counter should be cleaned or replaced before resetting but usually you can get away with resetting once.
1. Start with printer OFF
2. Hold down RESUME and then hold down POWER
3. Release RESUME
4. press RESUME twice, then release POWER
5. let green light blink until printhead has finished moving.
6. Select functions below with RESUME, execute with POWER

0 presses - green light - Test Print (exit service for i960)
1 press - orange light - EEPROM info print
2 presses - green light - EEPROM initialise
3 presses - orange light - reset waste ink counter.

This also applies to the i550, i560, i950, i960

Good Luck, I hope this helps?!

I have a IP4000 and had this problem with orange light flashing 5 times and then green. It also said 'operator error'. I removed all of the ink cartridges, gave the round plate that the ink sits on a wipe, replaced them and solved my problem.

Used Devdeep's and mssg's solutions together, worked perfectly for me. Thanks guys, you are stars!

I ran each of the test cycles, then took all the cartridges out, cleaned the 5 ink contact points and re-inserted them. Then I switched off the printer by holding down the power button for a while to get it out of the test mode, restarted and everything worked! Phew!