reply to Oregonian
Re: [Troubleshooting] MiFi 4620L Firmware Won't Update I recently got the 4620L and also have this very problem with firmware update. According to update log, I have attempted update around 10 times in different areas, web browsers, devices, etc. And they all resulted in a 403 failure after power cycling really quickly. At least I know it isn't just my device now.
Hopefully a fix will be discovered soon.