The "safe mode" indication is only really a warning that the control circuitry has shut down the mechanism as its detected a problem somewhere, and of course that can be anywhere, although in the largest percentage of cases its associated with the mechanism. Without any error code warning its impossible to diagnose where the problem might be, if you have tried the logic reset test by removing the battery then reinstalling it and this has made no difference, then it really requires some detailed investigation work to determine the source of the problem.