Apple Watch Series3 - three important tips (notes)
I wanted to see the Wallet card transactions from Watch app (on iPhone), and it blocked asking me to update to WatchOS8. The watch was set to auto-update, but had not updated for a long time. The update did not work, the watch crashed (black screen). The iPhone was update about 10 days earlier, to the latest version iOS 15.4 (this is the first thing to check).
The watch was restarting to the grey iPhone icon. Bringing the watch close to the phone, there is the "Recover Apple Watch" screen, with the code shown on the watch.
Entering the code, after a brief spinning circle it shows:
It turns out, the Apple Watch Series3 cannot recover on 5GHz Wifi, and I had disabled 2.4Ghz because there were too many (>15) devices from nearby appartments causing interference.
Note: to recover a Series3 watch, you must have 2.4Ghz WiFi.
At the Apple store, I was able to recover using the store-WiFi. After starting the recovery process there is the famous ring, which small lines showing the progress. The first ring too about an hour. Then the watch restarts to the apple logo - and the ring appears again. The genius staff told me this is normal. The second ring too about 25 minutes to complete. Apple logo - another restart. Then the ring appear for a third time, took about 15 minutes to complete. Apple logo - restart. Now watch OS could boot, and the watch was back. Update correctly to watchOS 8.5, and the wallet still had the debit card.
Note: The whole restore took more than 100 minutes.
As I was rebooting the phone and the watch, trying to recover it - at one point the watch app on the Phone asked me to un-pair the watch; asking for the iCloud password. In retrospect, to un-pair was a mistake. After the recovery the watch was back (wallet card and all) - but was not paired. In order to pair the watch, one has to erase the watch (on watch in settings). Then the famous circle appears again, paring takes about 20 minutes. The whole recovery took more than 2 hours.
Note: when recovering the watch, do not un-pair, even if the app asks you to.