my watch will not hold a charge

To understand Apple Watch performance and its relation to your battery, see:

Apple Watch - Battery - Apple

Apple Watch Battery and Performance - Apple Support

“Battery life” is the amount of time your device runs before it needs to be recharged. “Battery lifespan” is the amount of time your battery lasts until it needs to be replaced. Maximize both and you’ll get the most out of your Apple devices, no matter which ones you own. See the "Tips for Apple Watch" section in:

Batteries - Maximizing Performance - Apple

If the battery drains too fast after an update, see all the replies to:

Update 6.2.1 Battery Draining Too Quickly… - Apple Community

FWIW, in some cases, unpairing the watch, completely erasing it, then pairing and restoring the backup will resolve the battery draining issue after an update. Also, some people have found that simply waiting a few days after an update resolves the battery draining problem.

Horrible battery performance since updating to 7.5. Updated last night, charged as usual while showering this morning, hit 10% battery by 2 pm. A couple of months old Series 6. Before the update got through a full 24 hours with 30% plus battery remaining. Definitely related to the update.

See the replies to:

Battery Drain since watchos 7.4 - Apple Community