There are multiple clones and revisions of the WS-6906. Do not download software from random forums. Open the battery cover. Look for a sticker: or "V3.0" . You need firmware matched to your PCB version.
Do you have your or the RS-232 cable ready to start the process? Satlink WS-6906 Software Upgrade Guide | PDF - Scribd satlink ws-6906 software upgrade
: Click the Load Software or Browser button and locate your downloaded .bin file. Initiate Flashing : Next or Start . There are multiple clones and revisions of the WS-6906