No, it cannot load a separate bootloader. I tried to tamper with the loadercode (the "secure" bootloader), but it wouldn't boot. So I am guessing there is some third party (boot ROM) that verifies it.
Also, I think Linux always loads loadercode + mp1.img, regardless of the tamper state. The different code paths depending on tamper state are taken within the (integrity protected) loadercode.
Also, I think Linux always loads loadercode + mp1.img, regardless of the tamper state. The different code paths depending on tamper state are taken within the (integrity protected) loadercode.