Power button and eject button stopped working

Hi all. I have a CECHC01 ps3 that I've been repairing. When I put the power and eject board back in and try to test it I flicked the switch at the back and briefly got power going to the red light before it went out. flicking the switch at the back and the red light won't come back on again. I reseated the ribbon cables carefully multiple times and tried again and again but still, it seems dead. Does anyone know the cause? Is it a fuse that's blown on the motherboard itself or is the switch damaged? I don't have a voltmeter to check so I need advice on how to repair this fault. Thank you for any advice left.