| Symptom | Cause | Fix | |--------|-------|-----| | No USB detection | Not in FEL mode | Check FEL pin + GND short | | Stuck at boot0 | Bad DRAM config | Recompile with lower DRAM speed | | Kernel panic | Wrong device tree | Replace .dtb with correct one | | Boot loop after 15 sec | PMIC hold missing | Add hold_power_en in board.dts |
Always keep a known-working firmware .img file. Use PhoenixSuit’s Force Format (uncheck "normal update"). allwinner+a133+firmware+work