@wlodekwbw
I'd think that Bushwalker8 simply means for the OP to be careful with cross-flashing because of the differing HWIDs. For any degree of success, matching PCBs is of course essential. You'd be aware, as he is, that a PCB match alone doesn't for certain guarantee a safe successful cross-flash particularly if there's region layout/size differences.
@timstring
Safest way to do it initially is to use the original device's boot.bin combined with the donor firmware's other components and retain the original device's HWID however that sometimes doesn't work because of region differences. eg: converting 37x0>34x0 needs either a full flash or for a hybrid flash one of the fw's BIN files needed to be compressed (fw_all.bin or boot.bin, can't recall). Likely a hybrid flash retaining HWID will work and even if it doesn't it's easy to revert back in most cases.
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