Misbehaving HEQ5

Hi there, new to this forum. Well returning after a long absence really.
I'll start by seeking some advice on my Synta (Skywatcher) mount.
This is my first 'go-to' mount, though not my first GEM.
Its an HEQ5, about 2 years old. A new(?) handset with UTD firmware. Polar alignment w/in tolerance for visual, balance spot-on. Clutches - check - swing freely in manual and are tight for go-to.
Load well beneath rated capacity (5.3Kg / 17Kg)

I turn on the mount (mains power with 12v 1.25 amp adapter), and get the "don't look at the sun" spiel. Over and over and over. Pushing "esc" doesn't work, nor do either "align' or 'set-up'. Some random combination of the 3 seems to work, but each start-up is different.
Eventually I can get it to set-up by using the 'utility' menu.
Of greater concern is the fact that the direction arrows (L,R,U,D) don't work at all, regardless of what 'mode' I'm in.
I've read the manual 5 times, I've checked the firmware and hit 'factory re-set'. I've trawled various net groups and not found anyone with the same problems.

At the risk of tempting fate:
Once set-up, it "go-to's" fine. It tracks fine. It knows its catalogues. It knows where it is and what time it is. This is a 'pre-owned. mount, but I have no reason to suspect the vendour of any fault.
Is this some electrical gremlin that's gonna cost me $700 to fix, or am I just missing something?
Thanks,
Peter

Peter,
I don't know a thing about your particular mount but I think you may have a glitch in the initialization routine. I would try to update the firmware with whatever version you have as there could be something corrupted in the flash. Other than that you could have a problem in tha hand controller. I wish you the best of luck; having worked in the electronics industry for years these types of problems will cause you to go bald way before you get grey.
Dale