I was trying to install a custom firmware quite a while ago. The guide told me to go into recovery mode to install the firmware. I did not differentiate between recovery and service mode, and ended up getting a RSOD. I can't remember what I did but I got back to service mode. I thought that it was all too hard so I tried to downgrade back to 3.41 (I was on 3.55 at the time).
The USB just stopped doing anything, and I waited for ages so I just switched it off at the back. On the usb it said something about a manufacturing update error. Now whenever I turn on the PS3 it stays on for about 15 seconds and turns straight off again. No YLOD or flashing red light, just turns straight off as it usually would. Screen flickers, but no audio or video output on provided cables.
I CANNOT GET INTO RECOVERY MODE, SO DO NOT SAY THAT I SHOULD TRY AGAIN. It is a CECHG UK model BC 60gb Ps3. I have wiped the hard drive and it has not changed a thing.