What is wrong my watch just stop working? All i see is the red lighting bolt.

See this link, but if the Forced Restart doesn't help, you'll need to take or send your watch to Apple for service --> If you see a red "!" on your Apple Watch - Apple Support

Hello, my Apple Watch Series 5 also just stopped working. Yesterday, it started with my Apple Watch restarting multiple time throughout the day, then when the battery died. I placed it on the charger and now it will not hold a charge. I see that it is charging, but will not charge to more than 1% and, while on the charger, my Apple Watch still keeps restarting. I was able to restore the Apple Watch Series 5 to factory reset, but it will not stay powered on long enough to update the Software to WatchOS 8.3 (currently running 7.6). I have tried multiple charging cables and multiple USB outlets; Apple Watch still will not charge more than 1%. It is not staying powered on long enough to install the watchOS or to pair to my iPhone. I also cannot Power Off the Apple Watch, when pressing the power button, the option to slide to power off is grayed out. I am not sure what to do now.

I was able to update my watch and repair it to my iPhone. I removed the watch band and placed the charger on a flat surface. I believe that once the watchband was removed, it stopped the watch from moving out of range of the charger and it was able to charge successfully. I was also able to finally pair my devices, which took about 45 minutes; and then update to watchOS 8.3, which took another 2 hours. I'm not sure why the data transfer was so slow but I finally got it to work. I would recommend placing the charger on a flat surface, use 2 sided tape if it will not stay flat; then set just the watch face with no band onto the charger; also make sure the cable is not going to move so it doesn't knock the watch off the charger, tape will also work. I'm am not sure what may have caused the battery bleed issue, but if it was a 3rd party app, resetting the watch corrected the issue. Hopefully the update will stop this form occurring again. Thank you everyone for your support.

What you need to do is schedule an appointment at your Apple Store Genius Bar and take the watch to them for evaluation.