Drum Machine issues

[SuburbanMe]

I've got an R70 drum machine and it's coming up with 2 errors. Serial error and Act sensing Err. That's how they are displayed on the unit. These errors come up when the unit is both plugged in and not plugged in.

Anyone familiar with this unit and/or these errors?

All help would be appreciated.

Luke.

EDIT: I should also mention that this unit has been "fixed" for these issues by a Roland service agent in the past.