How I fixed my E2.
First of all, I open the case, disconnect the 10 wires link (10 cm) between power supply and motherboard. I put a big external ATX power supply from my home PC.
I swap the IDE cable with a brand new I have at home, but the one I putted is only for test (one plug is not on the good position, have a look on regular IDE ribbon and you will see what I mean)
I'm lucky and I have in stock a golden disc from Escient to set up new hard disc drive so I putted on my E2 a new HDD (750 Gb IDE)
Escient explained that when you want to do a manual firmware update, you have to disconnect your LAN.
ok, all ready, let's go.
After 5 minutes, update disc didn't boot... (bad news)
So I decided to reboot the machine with LAN connected !!!
>>> after 2 or 3 minutes of LAN activity, screen told me : update in progress, please wait (downloading) GOOOOOOOOOD ! downloading of the firmware took 10 minutes or more.
flash succesfull, reboot the machine with golden disc inside and 5 minutes later, a working E2, like new.
After that, I reconnect original IDE ribbon and reboot >>>>> ok
I reconnect original power supply and start again >>>>>> ok
So, my experience is that sometimes, electric problems on your AC power may hang your motherboard, and as Escient did not put a BIOS RESET switch, you have to force the system with a new firmware update (that will reset your bios conf)
Of course, if we need a perfect power supply, you have to check your capacitance on P/S as Stefuel said !