Hi llorenzo313
Many things could have gone wrong but for sure your battery specs are enough for the raspberry pi and pix hawk. I’ll list things that you could check. Focus on the third point.
- Check that your power module is working fine
- Check the cable connecting the pix hawk to the raspberry
- Check that your battery is actually able to provide the required voltage. You can check the voltage of your battery easily by connecting it to your battery charger. Sometimes the LIPO battery cells are not equally charged which results in low overall voltage. I have had this issue before. If that is your case, then you can find many youtube videos explaining how to solve this issue depending on your charger. In some cases, you’d have to throw away your battery and buy a new one