RouterOS V7.xx not accesable after upgrade on a Metal 52ac

Hello all,
I had several years a Metal 52ac but after upgrading from 6.49 to 7.11 it functioning normal but I do not get any access
So I baught a new one because my reset button was broken.
I upgrade the new one and also after upgrade no access with winbox or webinterface and I cannot reconfigure it.
It send it for garantee and I get a new one.
Do they know anyone it?