If your Nebra Helium miner is Offline and not earning any HNT there are a few things you can try to resolve the problem.
Take a look at the LED lights on the back panel of your miner.
It is normal for the green light on the back of the unit to blink rapidly about 8 times with a few seconds interval. This is the expected behavior.
There is an orange or yellow LED below the green light and if that is off or both LEDs are off, then there’s an issue with your miner. Here’s what you can do to solve this problem.
The first thing to do is power down the miner. Then open the lid of the miner (you don’t need any special tools for this) and re-seat the Raspberry Pi compute module. Power the unit back on.
If the problem persists – that is, the Yellow LED is off, then it’s most likely an issue with the eMMc card shown in the picture below [blue rectangle]
You can contact Nebra [email them at email@example.com] for a replacement card. Note however that it will take around a month for them to send it out. If you don’t want to wait that long, then you can simply purchase a replacement card from eBay. The 64 GB SD card is a cloned version of the eMMc card and works quite well. Some Helium miners have reported improvements in mining performance once this change is made.
Once you receive the SD card, you can replace the eMMc card with this one and you should be back up and running in no time.