I had the same problem with my pixel 3, it had a faulty power button that would keep stuck on pressed and force a reboot
How I "solved" it:
- Use a TPU cover
- Only block the screen with double tap on empty spot on launcher
- Only wake up with double tap on screen
Symptoms that I had:
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If I enabled the emergency mode that sounds alarms when the power button is pressed 5 times in a row very fast, it would accidentally sound the alarm if my finger touched the button
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I could not easily turn on the phone if it was turned off
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The phone would sometimes bootloop until I gently smashed the phone on the side on the corner of a table (to unstuck the button)
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If during the "bootloop", I pressed the volume button, it would go in recovery, which indicates the power button was stuck
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Without the TPU phone cover I could lock the screen with a very very light touch on the power button
I didn't get to ask how much money was required to fix it because shortly after I accidentally dropped it and got green hair lines on the screen, so I just sold it for parts on ebay