@willingzhu
The bin file for region 154 contains device-specific information which should not be written to a device other than the unit from which it was dumped. Regardless, the device re-writes it's own specific information to rgn154 on each and every boot cycle. It was the flashing of the APAC HWID 2996 firmware that has changed the device and not the writing of the 'foreign' BUP_154.bin. In fact by first writing another device's non-vol memory info to it you ran the risk of introducing incompatible data into its NV memory which could have prevented it from ever booting again while not contributing anything of actual value for the conversion. As the device is now an APAC device with HWID 2996, GarminExpress should offer to supply compatible voice files etc. I'm unsure about the traffic receiver updates though.

Even when there's a commonality of PCB P/Ns is still always best practice to attempt a hybrid-conversion first using the original (2588 in this case) ramloader aka boot.bin from the native firmware combined with the remainder of the doner firmware (2996 in this case) but with the HWID changed to original (2588). Using original boot.bin and retaining HWID makes for easy and safe recovery if the flash fails. If a hybrid-conversion is successful then a full flash will be safe. If a hybrid is unsuccessful it could simply be that the original ramloader is not capable of starting the boot process with the 'new' fw in rgn14 and it'll boot-loop, freeze on logo or show 'system software missing' but will be fully recoverable. If it's unsuccessful because a 'new' complete fw is totally incompatible however you may end up with a dead brick that'll never boot again and won't even turn on.