Really sorry to read your continuing problems.
I think it will not help to let your Clip Sport battery completely discharge. Are you able to shut it down by a 20+ sec press of the Power/Select button ??
I can only think of one more solution.
(If your player has discharged by the time you read this suggestion, try connecting to a 1.0 amp charging block using the original micro USB cable.)
Hold down on the Back button (aka Lock button) and the Power/Select button at the same time for 30 secs or longer?? Then see if the player comes on with a normal 3 sec press.
Beyond this advice, I fear there was a problem with your attempt to install Firmware 1.38. I have not tried this version on my Clip Sport (still using 1.28). Make sure your upgrade.hex file has the filesize 28,491 kb.
Hopefully, a few senior SanDisk Forum members will provide more useful advice for you??
