My original Pebble smart watch (purchased refurbished) started to have a problem where the display would get corrupted. It mostly only occurred when I was pushing a button to change the display, or when my stopwatch/timer was running (updating the display continuously). For day to day use of just wearing the watch, the screen would be normal much of the time.
I thought at first that something was just corrupted in software, so I removed all of my applications, but that didn’t fix it. Then I reset the watch, and that didn’t fix it. Then I rebooted the watch, and that didn’t fix it. Then I reset the watch to the factory default settings with a super hard reboot and reinstall (removing the custom firmware I had installed), and that didn’t fix it. So, I admitted that it was probably a hardware issue, and found this page on the pebble website that talked about “screen issues”.
I’ve found lots of information on the Internet that tells me this is a problem with the internal ribbon/zebra cable connector not staying connected properly.
I found this video that tells how to fix the ribbon/zebra cable connection issue by adding toilet paper in the back of the watch to hold it down.
If you don’t like opening your watch, and trust that it is actually water resistant, I also found this youtube video how to try and fix it by putting it into hot and cold water (but that doesn’t fix it permanently).
Luckily for me, I was apparently still within my 90 day refurbished watch guarantee, and Pebble is swapping out my watch for a replacement, so I don’t need to stuff toilet paper in the back of my watch. If you experience this type of issue you should report it to Pebble quickly. It appears to especially plague early Pebble / Pebble Steel watches, I presume they have changed their manufacturing process to keep it from happening to the later ones.