Black screen locked after MSTMS patch

Hello, I have had this problem on a lot of nav 4 models. Via52 go500 go400 etc. Before the device freezes it is possible to check what
maps the patch thinks are on the device. If the patch is removed mdc often disagrees with the patch on what maps are installed.
If you remove all maps with the patch, then remove the patch, connect to mdc and remove all maps seen by mdc.
Then apply the patch and install the required map the problem of freezing seems to go.
I do not know all the files on a nav 4 device but it is as though what used to be the the tt bif file on nav 2 devices is incorrect for
what is actually on the device causing the freezing. Do a reset before re applying the patch!
Hope this helps.