Hi Antony,
It sounds like you're still dealing with the ongoing effects of water damage. In fact, you might still have moisture in your phone. As many community members can confirm, water damage can often show up hours or days after the initial incident. I'd recommend powering the phone down, pulling the battery, and taking care of any remaining moisture and residue.
You'll probably want to disassemble your phone and clean it before you power it up again. We don't have guides for the ZenFone 6 yet, but there are a [https://www.youtube.com/results?search_query=asus+zenfone+6+disassembly|few videos|new_window=true] on YouTube that could prove helpful. Be sure to check out our [[Electronics Water Damage|Electronics Water Damage|new_window=true]] page for help taking care of the water damage. Hopefully, this will fix the problem and prevent anything worse from happening. Good luck!