That's where the guys on the thread said previously to people "get back on your original train". The modified ones can't be updated further from that point, not in the normal way. I note @leonlad is on 5 series now. I suspect the toolkit helped. Think the Turkish guy left a series of issues around as Polish retrofitters did in the UK in the past. Been there done that. As a few others.
The reliable retrofitter and board sponsor is this one :
I note they ask for the 2xx units to be returned if they want 4xx or 5xx with tiles. It's the way the update works else it may brick the unit. Then you short some pins inside to get it back if DIY it's on the net. There might be techniques which are more DIY to that 2xx to 4xx / 5xx. But if doing it yourself be prepared for it to be bricked and know the way to get it back if not UK based. East Yorkshire have fixed with bricked units from the board before and their associate up there. These were round that Turkish software as I recall. I arrived late to the party. Only the Poles were messing up mib2 highs with their antics in the UK of miss selling map and firmware updates. Those had to be sorted out by East Yorkshire or DIY which had progressed a bit with the mib2 high tool kit and 1447 AIO. The bricked units are an expert or the screws out. Expensive kit to mess up. Mib2 highs are more forgiving with train jumping, mìb2 standards aren't.
Agreed, given the posters firmware has jumped trains so personally I'd not bother trying/risking to upgrade the firmware any further and just concentrate on trying to get the maps updated (any firmware updates won't help with that!).
Rolling back the firmware I think involves rather invasive techniques (taking the nav/cd unit out, connecting to PC and shorting pins on the circuit board, that kind of thing!).
Here's an example of what can happen with a firmware train jump and the recovery needed (and how to get back to MST2_EU_VW_ZR_P0254T firmware):
