it is unclear if you tried a two button reset:
- Press and hold the power button on your Surface for 30 seconds and then release it.
- Press and hold the volume-up button and the power button at the same time for at least 15 seconds and then release both.
The screen may flash the Surface logo, but continue holding the buttons down for at least 15 seconds. 3. After you release the buttons, wait 10 seconds. 4. Press and release the power button to turn your Surface back on. You should see the Surface logo.
if that does not work, can you try someone else's typecover on your SP4 and
yours on theirs?
if you are in the US, go to a physical retail Microsoft Store and they will
assist.