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?

What file you flashed to router? Can you ssh to 192.168.1.1 ?

I also doubt this "bricks" the router. But I can see that it would make it not functional as a router for your use case.

It is certainly possible to change the mac address to what your (presumably provided by the carrier?) previous router had.

Setting vlan ID's is certainly possible, but getting IPTV to work without very clear instructions and support from the carrier might require a lot of effort?

I have no experience in getting what I presume is a multicast iptv distribution system from an ISP working?