As i already answered, you CAN go back to work at old H1B location if H1B amendment is denied.
‘Out of Status’ will happen if you DO not go back and work at old H1B location.
Since, you are ONLY authorized to work at a location and with a status mentioned on your i94, your H1B amendment denial means that you cannot continue work at amended location.
If you continue to work at amended location even after denial, then you are violating the terms of your H1B visa.
However status shows as “case was approved” I think my request for premium (filed by employer)was not accepted otherwise the status should have been “Case Was Received and A Receipt Notice Was Emailed”.