Openwrt MR90X help me

Hello, good forums.
My previous attempt to install OpenWrt on Mercursys MR90x resulted in a brick due to an unknown error, and I had to request a replacement. Could you help me during the OpenWrt installation process?
https://openwrt.org/toh/mercusys/mr90x_v1

Since we don't know what you did "wrong" last time, it'll be hard to avoid repeating the same mistake.

My internet service provider uses MAC filtering. I can't get an IP address without changing the MAC address in the stock firmware. I don't have internet access when installing OpenWrt. Also, I can't get internet access from the IPTV/VLAN section without setting the VLAN ID. I think the error bricked because of these. Could you help me with this?

I doubt it, none of these would brick your router.

"This", is what exactly?