There was a thread here where some guy recommended to unroot phone with this method. I've rooted it natively with that shortcut method (com.meizu.root… etc).

It was trying to unroot for too long. Someone said that he rebooted the phone, tired again and it worked then, but what I've got is that it stopped booting, it does it forever (bootloop). When I do power+down, I get «Fastboot» on the bottom and logo. Nothing else happens, it seems. When I do power+up, it loads some menu, suggesting to update and wipe the data. Wiping the data leads to the same infinite boot. I don't know where to get stock rom or some update.zip to fix this.

Please, help. Other phones have so much support on the internet, but I cannot do anything with it.