W211 clock stopped??

[Kingcoleriding]

My 2007 W211, possibly on start-up, had the seatbelt warning light illuminate (no accompanying warning buzzer) and, at the same time the clock stopped! I reset the clock in the menu but when pressing the R (reset) button the time reverted to stopped time and reset to that!! Seatbelt light also stays on. Any thoughts very welcome, Tks.