DuxBellorium Would a bad battery cause this and is it replaceable or am I looking at total data loss and a new phone.
A battery failure seems plausible. Repair shops do replace batteries, though given the age of the device that might or might not make sense.
Whether or not there will be data loss depends on what went wrong.
DuxBellorium Last Saturday (today is Thursday) it went through the charge cycle when you get a new Pixel, displaying a percentage as it slowly charges up.
How long did it take to fully charge? If it hasn't charged yet, that would suggest a battery failure.
Will it boot while connected to the charger?
DuxBellorium Odd that it did it on reboot after the update.
It's not that odd. Some problems show up only on a reboot, and many devices don't reboot often. Some problems show up only when a lot of data are written to the storage, which an update does. Some problems show up only when there is a substantial quick battery drain, which an update does.