W56H initializing/boot loop

[n.vangelder]

Hello,

I recently found 3 old W56H handsets laying around and according to this website they are compatible with the Microsoft SIP gateway, when I updated them to version 61.83.188.7 they got into a loop where they start initializing then restart, start initializing again, restart again and so on which I can only seem to get rid of by disconnecting them from the base station, I tried it with a W60B as well as a W70B and I experience the same issue with both of them. Is there any way to update/downgrade these handsets to a working version without them being connected to a base station? or are there any other solutions to this?

Any ideas are very welcome.