A metal razor blade will scratch the plate and create uneven heat distribution. Chipping away at the powder coat can also lead to rust. If you need a scraper, try using a plastic edge from a card instead. Turpenoid is odorless and will dry quickly without leaving any oily residue or citrusy smells. The magic eraser works great for cleaning off impossible dried up grease off pots and pans, and works just as good in cleaning up leftover 3M adhesive with some Turpenoid. While the instructions suggests to use water with the magic eraser, it's not what you want evaporating inside your 3D printer. There are tons of exposed wires and circuits that can easily short circuit. The problem with using acetone other than its heavy toxic odor is that you may inadvertently create an acetone bath inside the printer, melting the ABS or PLA already loaded in the extruder. 100% isopropyl alcohol would be a better option as its recommended to safely clean electronics.