E250 not recognised

We have 3 E250’s in family. Have upgraded firmware without drama on 2. The Computer is not recognising when attaching to USB. Using firmware upgrader then when it is recognised wants me to change from MTP to MSC and once disconnection is made back to square one.

Have tried return to factory settings but the cycle is endless.

Suspect if I can get USB recognition I may need to format.

Any ideas?