Revo R3700 won't boot from USB / CD

discoloop

Revo R370, O/S died and can't reinstall because I can't boot operating system from bootable USB or liveCD.

 

 

On power on when external drive is plugged in:

- System beeps

- Bios identifies RAM ("Single channel mode")

- Then freezes. Cannot enter bios. (Light on USB keyboard stays off, suggesting no power to device. Lights on external hard drives are on, suggesting power is getting to them.)

- After a while, boot proceeds to internal HDD and power gets through to USB keyboard.  Next step in the boot is the RAM test.

- I CAN mount external drives from what's left of the OS on my internal HDD.

 

Notes:

- Boot order in BIOS is places CD and USB devices before internal HDD

- Have tried resetting cmos via jumper and battery disconnect

- Have tried different USB ports and cables.

 

Any ideas?