Celestron CGem DX Mount has stopped working HELP!

My CGem DX eq Mount has stopped working.
Just the initial alignment. It is as if it thinks its located in Southern Hemisphere or something. It wont do an initial alignment without slewing into the ground, and I cannot do a proper alignment routine. But if I find, say, Jupiter, it tracks perfectly.
Firmware updates done, factory reset done, internal battery changed, change of handset doesn’t solve (two different handsets used in this video, with two different results). I have obviously checked the settings in the handsets for time, location and tracking EQ North.
Instead of taking it all apart, shipping it to a repair centre, pay hundreds (when its probably just a ribbon connector somewhere), wait weeks, and put it all back.. only for it to work for 6 weeks before breaking again, DOES ANYONE HAVE AN IDEA on how to SOLVE this?
The problem surfaced after changing the internal RTC battery. But I suspect optical sensors/wheels in motors?
internal calibration strips.. I dunno how it works? moisture on the tracking measurement device? Has the main board died?
#Stoopid 'obby.

[@heliczer]

Many thanks for your reply! Yes, I have tried a few things... The mount DOES always seem to know where Home Position is, and once a target has been found, seems to track perfectly. But the good news for me is that I think I might have sorted it this weekend. I just need a couple of clear nights to confirm - cloud-solving right now! I suspected the hand controller so took that apart and gave it a good clean, especially the contacts and rubber actuators. What (I think) made the biggest difference is removing the caps off the motors and cleaning behind the optical encoder wheels(?) and optical sensor with a fine cotton bud and Isopropyl. I am somewhat amazed that any level of accuracy can be achieved with these tiny plastic wheels mounted on these small motors, but there we are!

[@zborkz]

You may have already tried this but.....Have you disengaged the clutches on both the RA and DEC, and send the command to park the mount? Then manual placed the mount into the parked position and then reengaged the clutches, then attempted to slew to a target? If that fails of failed, use ascom drivers and a program like NINA to try to control the mount directly bypassing the hand controller. Have you done any plate solving and compared the results to the hand controllers reported position? My initial reaction is the mount doesn't know where it's orientated to begin with.