Did i fry my Mobo?

a75 pro 4m, asrock

older pc that some intermittent reboot problems. Have it on my desk to take it apart and put it back hoping it would repair itself. Figured out that the 20pin (24?) power supply would cause it to reboot. Basically, although jammed in to the board, it had enough room to move and reset.
SO...jammed it in and installed 10, multiple reboots. Came home to reboot for more updates and it stuck on the bios. I wiggled the 20/24 cable ( ) and off it went.
Power is getting to the board. USB thumb lights up, vid card inserted lights up but I can't get it to reboot.

Thoughts?

Strange.

The ATX power cables I've seen each have a clip that locks the connector to the motherboard. If that's engaged, there shouldn't be much play in the connector.

I don't know if you can damage the motherboard if power is supplied and the ATX connector isn't seated properly.

The MB has a 24 pin connector, but it is also supposed to be compatible with a 20 pin, should your PSU be that old.

If the plug is seated properly, the first thing I would do is disconnect it and check to make sure plug and socket connectors look OK.

If the motherboard capacitors have developed some load, it could not switch on properly. Remove the power cord, press the power on button several times to discharge and then put the power and try again. Also check your PSU, it may be faulty.