Hello,
Thank you for your answer
I managed to resolve this problem. The AT command would not respond to commands like AT+WOPEN=0. But I found that the command AT+WDWL would be the only one to actually work. I sent the bootloader and firmware through XMODEM-K1 https://mycusthelp.net/SIERRAWIRELESS/_cs/AnswerDetail.aspx?sSessionID=&aid=487. The device is now functional again.
Thank you.