Think the Tilt is wrong?
My guess is it probably is the tilt. It will give false reading due to yeast caking, Co2 and not properly tared (is that even a word?). With that said, I tared mine last Sunday, set it up per color and beer, sanitized and plopped into the fermenter only to give me an instant read of 1.006 Next day it gave the same read. Clearly a failure. Weakening battery? possible but doubtful.
Take a sample and check with a hydrometer.