Hi @lamadelon
Could be either or both. You won't know until you open it up and check to see what's wrong.
It does seem too coincidental that the watch failed after being immersed, so presumably its waterproof integrity has failed somehow
If there is evidence of corrosion then you would need to dis-assemble the watch and clean ''all the affected parts'' using ***Isopropyl Alcohol 99%+*** (available at electronics parts stores) to remove all traces of corrosion and water. If possible do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain additives which may leave conductive residues and is not as effective. If you do have to use it check the label to verify the amount of IPA. The higher the percentage of IPA the better
Here are some links that may help.
[[Electronics Water Damage]]
[[Topic:Huawei Watch GT 2e]] repair guides
As always with electronics, especially surface mounted pcb be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the board. The ends of any flex cables and their connectors need to be cleaned as well
Hopefully after you have done all this the watch ''might'' possibly work correctly again.
If this process seems too daunting, take your watch to a reputable, professional electronics repair service, experienced in liquid damage repair and ask for a quote for a repair. If you decide to do this, ''do it sooner than later''.
FYI, here are some links that may be of interest, regarding Huawei wearable products [https://consumer.huawei.com/en/support/content/en-us15851428/|water resistance ratings] and [https://consumer.huawei.com/en/support/content/en-us00738723/|definitions].