Even i am facing the same issue from the last one month. I have tried all the steps mentioned above. Visit service centre they flushed software and now I am on the latest firmware.99 version. Did factory reset thrice with in a month. I am unable to connect WiFi and whenever I try to connect my WiFi phone freeze and restarts itself. Last couple of days when I try to open camera it restarts. I think it's not user specific and it's across all the users. I have seen many Zenfone 5z phones for sale in OLX. As many Zenfone 6 users complained about the updates that resulted in faulty motherboard, I guess the same happened with my phone. I got the phone in flipkart BBD in 2018, now in this BBD looking for another one. In this 2 years time period issues faced are battery draining, charging port damage that costed me 1500₹. After shelling out 27k I felt I made a terrible mistake purchasing this. Whomever read this post certainly say that this is not a good option I made. Many users were facing the same issue and it's not coming into lime light as they don't know that they can post in this forum.
@adityapruthi2001 ,
@Sufyan if you can find any updates or solution to this let me know my email id is srinivaassiddu@gmail.com.