Chargers for JB Multimedia and JBR20 V2

[jlovda]

These two units look identical and use the same 2200ma, 4.2v Li battery.  I'm wondering if I fried the charging circuitry in my JBM.  I tried charging the JBM with my JBR charger and the bottom of the unit got very hot.  Now I can never get the battery indicator to go above 50%.  The JBR charger says 6v on the label but I later checked it and it measured 9.5v open circuit!  The charger that came with the JBM appears to be a switching regulator type (very light weight) and measures 5.0 v open circuit.  Both chargers use identical plugs.  Originally I didn't think one volt would make a difference.  Am I dead in the water now?
Thanks