You cannot fix what you do not measure. To check your current version, follow these steps:
Write this number down immediately. It is your baseline. fiberhome sr120-a firmware
You cannot. Use the physical hardware reset button. Hold for 30 seconds (Lights should flash), release, wait 2 minutes. You cannot fix what you do not measure
Before you try to force a generic or "unlocked" firmware onto your ISP unit, consider the risks: Write this number down immediately
Avoid: Random Google Drive links, "free firmware download" websites (they often bundle malware), and eBay listings selling "unlocked firmware."