Unable to verify update

I have an Apple Watch SE (2nd generation) that was exposed to water a long time ago and stopped working. Recently I managed to power it on again, but it is completely reset.

When I try to pair it with my iPhone 13 (iOS 26), I’m forced to update the watch to watchOS 10.x. The update downloads, but when installation starts I always get the error:

“Unable to verify update. The watchOS update could not be verified because you are not connected to the internet.”

I am definitely connected to the internet and have tried Wi-Fi, mobile data, different networks, resets, and manual pairing without success.

Has anyone experienced this before?

Could this be caused by hardware damage (for example Wi-Fi/Bluetooth corrosion from the earlier water exposure), or is there any known workaround?