Hi Dave, I wasn't having a whinge (apart from the back light flashing briefly when the meter turns on). I'm grateful for all the help you've given me over the past couple of years. I did rename the file, but I put it on a different Micro SD card. It was the card out of my phone and I wasn't sure which way to format it, so tried formatting in Windows 10. That must have been the problem as when I put the bin file on the original card and booted it from there it worked. I was worried as I couldn't remember whether to rename the zip or extract the bin file. It sounds stupid now, but I've only updated the firmware once before and that was when I first received the meter and updated straight to V1.57. I love the 121GW. I've got both your meters, cases, lots of fuses, and even brought a BM235 for a friend! I'm still a beginner and try my best, and am sorry for the annoyance.