HL8548 Modem firmware update error

Hi have been stuck with this issue and I can’t really find a solution to this modem firmware update error. Please bear with me.

I am using AirPrime - HL8548 modem. and have been having problems with he firmware update.(FIRMWARE LINK)

The latest modem firmware is 5.5.25.0. The firmware version in the modems I receive is 5.5.18.0
Every time I do a modem firmware update any versions from 5.5.24.2 below to the latest, it fails.

Here is an example of an update form 5.5.23.0 to the latest:

AT

OK

AT+CGMR
RHL85xx.5.5.23.0.201610311418.x6250_7

OK

+WDSI=8191AT+WDSS?

OK

Preparing Firmware upload...
AT+WDSS?

OK

AT+WDSD=12570024^U
Sending ./hl8548/RHL85xx.5.5.25.0.201804161340.x6250_2_DWL.dwl, 98203 blocks: Give your local XMODEM receive command now.
Bytes Sent:12570112   BPS:70734                           

Transfer complete
Prepare firmware programming...

OK

+WDSI: 3
ATI
HL8548

OK
Start Firmware programming...
AT+WDSR=4
OK

+WDSI: 12

+WDSI: 14
^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@
Error updating modem firmware

It gets to “+WDSI: 14” but does not proceed to “+WDSI: 16” which is a success update status.

It seems that it is fine updating from and to versions 5.5.24.0, 5.5.24.2, and 5.5.25.0. Also from 5.5.22.0 to 5.5.23.0.
It seems to be an old firmware issue. In this case, what are my options?