Atrix 4G update via OTA with unlocked bootloader? I am running 4.5.91 currently on a rooted and unlocked Atrix.

Will I brick my phone by updating to 4.5.141 from OTA source?

Can I re-lock the boot-loader if that is the issue?
I don't think it's possible to re-lock the bootloader of a Atrix 4G. You should read this
too