[achapman]

A further note on this. I've just bought a 4500 which has the same fault. Initially it would power up as the power was connected and pressing the power switch wouldn't power it down. Lately it won't power on and again the switch doesn't work.

I removed the switch assembly from a Snap 4400. This is very similar, but not identical. Effectively it appears that the 4500 switch board is an extended 4400 part with the addition of a white reset switch to the left of the black power micro switch. This means that the board is longer and the left mounting screw sits about 10mm further to the left.

As well as the power button working correctly, the two network LED's work as does the system LED. The power on LED doesn't illuminate though, so as a temporary fix it is usable.

The cable and connector that connects it to the disk backplane is identical to the 4500 switch board. I therefore tried the 4400 switch assembly on the 4500 and it works. The 4500 will now power up and down, confirming the 4500 switch board is faulty.

Since I'd rather have my 4500 working than my 4400 I may leave the switch board on the 4500 for now. I imagine getting a spare part may be tricky as I haven't a service contract with Overland.