First off, I've made a minor edit to your post as I really don't like to see swearing in the forums, please be careful in future
Secondly, from the photos, your machine appears to be in a good clean state. As you say, that expansion card is a pc emulator - the machine should probably be run without it while you diagnose this problem. I have heard of people having problems where a psu in a MSTE has started chucking out high voltages and fried some ic's on the board. I hope this hasn't happened in your case.
First thing's first, check you have good +12 and +5 with the psu disconnected.
Then cast a beady eye over all those caps on the board - any that look suspect should be replaced.
Give all the socketed ic's a firm push
Power it up, check you still have a rock solid +12 and +5. Check that none of the ic's are getting too hot too quickly (this would indicate a fried chip - not of the McDonalds variety).
Also note that if your MSTE has tos 2.05, there is no Atari logo on startup (screen stays blank) and it takes a loooooong time to complete it's ram test before it actually boots anything. If your press space, the ram check is skipped and the machine will attempt to boot from hd or fdd.