Mertik Maxitrol GV60 B6R trouble shooting

Hi everyone I have a gas fireplace with a Mertik Maxitrol B6R-R8PT2 control unit. It has recently stopped working, and I’m trying to figure out what the problem is. The small challenge I have is that the 8-button remote screen has died a long time ago, but is otherwise working fine. This means I can’t see any fault codes.

Symptom: pressing and holding power button on remote, the control unit beeps and whirrs a bit. Then after 5 seconds it beeps once again, then nothing.

I’ve tried: replacing all batteries. Re-setting and re-pairing remote.

When I press and hold the up button on remote, the on/off regulator dial moves freely, and then goes back to off.

The control unit is set to “on” and not “manual”

I suspect it may be something with the igniter but not really sure. My original installer has closed shop after covid so I’m trying to figure out if it is something simple (not gas related) which I can sort out myself.

Any advice would be much appreciated