iMac 2019 Mac OS fails constantly and needs re-install

Ordered a new iMac 2019 upgraded to i9 with 1tb ssd few months ago and got it in the beginning of May.

The computer worked fine for almost 2 weeks (2 users connected to iCloud and Xcode only) and that one day I found it stuck on apple logo. did reboot twice and it didn't work, the 3rd time I rebooted the computer caused a short circuit and wouldn't turn on again. I took my new broken very expensive computer to the authorized service provider (we don't have an official Apple care in Israel) and got it back repaired after a month, been told that the back panel and lcd were replaced.

When I got back home, I connected the computer and experienced lots of system failures like spinning balls and system preferences errors. tried to reinstall but failed because of an error "can't remove older system". so, I booted from usb, formatted the SSD and installed new clean os. the os crashed again 1 day after, did this re-installation process 3 times and every time the system crashed 1-2 days after and got stuck on apple logo. I use big data (more than 700GB iCloud Drive and photo library) and most of the time it crashed during my data copy. the last time it crashed I couldn't boot from USB or recovery and even after 2.5 hours with apple care on the phone we couldn't boot the computer into recovery or USB boot.

I took the computer back into the lab, and few days after they told me they fixed it by erasing and re-installing the os again. I was afraid that the problem won't occur again so told them to make more tests. again and again they told me they see nothing wrong.

Its in the lab now for 2 weeks already and I'll get it back next week. I'm afraid that the problem won't appear again after 1-2 days of usage...

I'm very disappointed with this apple experience, I own this computer for almost 3 months and actually used it only for 2 weeks.

I'm a big fan of Apple and an IOS developer and bought many iMacs, MacBooks, iPhones, iPads and more devices but this is the first time I experienced such a bad experience with so expensive device.

Did anyone else had these kind of problems, do you think it's and hardware error or is it reasonable that the service was able to fix it?

I really hope to get a working device already.