Sony a100 wont turn on - Sony Alpha DSLR-A100 Digital Camera

The A100 uses sensors near where you place your eye. Make sure the rubber eye cup is clean, and does not block these sensors.
as a test put your finger on them while holding camera away from face ( located just below eye cup) then you will see the view finder light up. If not problem is the sensors.

hi Kaitlyn.
see if this link helps you to find out why.
A100 won even turn on
or this one.
https://community.acer.com/en/discussion/41413/acer-iconia-tab-a100-wont-boot-anymore/p2
or this.
Help my Acer a100 won power up

Before attempting to take the camera apart, make sure to refer to the user manual. It will contain diagrams and schematics for the device:
Sony Alpha DSLR A100 manual

Check the memory stick if its full and delete some photos......then try and take a shot.
the four red zeroes are counters for the number of shots u have taken.....it simply indicates you have a full memory stick.
Mine played the same trick on me too.

It's actually, believe it or not, an anti-dust mechanism. All Sony Alpha A100's (mine included) do a little shake/vibration to help keep the dust off. It's nothing to worry about unless it lasts for more than a second.

What card do you use on the A100? And what capacity? Are you sure you have inserted it in the correct way? Be careful while inserting a CF card because of you insert it wrongly, it can damage the camera. Zooming is done using the zoom ring on the lens barrel. Just twist the zoom ring. Hope you are using the 18-70mm kit lens with the camera.

Try turning the camera off, take the battery out, reinsert it. If that doesn't work, the manual says to contact your local Sony dealer. You might also want to try taking the lens off, making sure nothing is hindering its communication to the camera body. Try using another lens if you have one.

Same here. My camera gives me the same error code unless I shoot with the largest aperture/smallest F-number.

IT happened to me.
When you're in the reading picture mode, go in menu and re-format your memery card.
It will fix it instantly.
Good luck

This error message is an indication that a problem may have occurred with the aperture assembly in the camera. To resolve this issue, service will be required.