What year is your Sprinter?
If it's a 2004 .... TAKE IT BACK TO THE DEALER ... they will HAVE to replace the instrument cluster to complete the recall.
(some 2005s are showing this symptom, too)
(you can avoid battery death *sometimes* by turning it off .... wait 45 seconds to see if the dash display goes away.
If it doesn't, try simply turning the key on and off again (no need to start it)... wait the 45 seconds....
If that doesn't work, disconnect your battery (the negative post is recommended) and at least you won't kill the battery.
--dick
p.s. the T21 thread actually starts here:
https://sprinter-source.com/forum/showthread.php?t=57401
I was visiting Janacooper while her Sprinter was going back and forth to the shop.
(recall done, came home, battery flat next morning. Tow to dealer, rinse repeat, until finally resolved (took 3 weeks?))
Now-a-days the dealer network (or their support) should be aware of the issues (MB and FL more so than Dodge)