I've had a v1.6 Xbox with a pro-fitted Xecuter 2.6CE since 2005 and its been pretty much perfect until recently.
On two or three occasions its refused to boot either via the Power button or the Eject/Close button. I get a green/red flashing LED typically indicating a hardware error. Sometimes it does that once and then shutdown, others times it frags.
However I found that if I shutdown, switch the chip off, boot to Error 5 (unlocked HDD) then switch off and reboot with the chip back on everything is back to normal.
But yesterday I noticed something else weird: the chip has two 512K banks with the originally supplied custom EvoX BIOS on both. The only difference between them is Bank 1 has the EvoX logo and Bank 2 doesn't. I usually have it set to the EvoX logo one but now it has swapped to the non-logo version on boot. It doesn't seem to matter whether I switch banks or not.
You might think a connection problem with the switch array ie. it is stuck on Bank 2 but, here's the weird thing: if I Reboot from my Unleash main dash or IGR the EvoX logo version BIOS appears to be used.
Never heard/read about anything like this - any ideas what is going on?