ESM update launched in Windows won't stop

Update launched in Windows Srv 2k8 (SBS) ran 20 minutes, then said it 'failed'. Rebooted several times, tried booting OMSA setup disk, but can't get into it because server non responsive for too long to complete boot of OMSA. Fans run 100% for about 75 seconds, then normal for 15 seconds, then back to 100% for 75 sec, then 15 seconds of quietness, and so on.

Tried running racadm racreset, but get message firmware update already in progress and no communication"

Seven y/o T410.

How can I force failed update to stop?