| Problem | Likely Cause | Solution | |---------|--------------|----------| | No output on serial | Wrong UART pinout or voltage | Use 3.3V, check pin mapping | | Stuck at “Starting kernel” | Bad device tree or initramfs | Check console= argument, rebuild DTB | | Boot loop after logo | Filesystem corruption or wrong partition | Reflash system/vendor images via FEL | | DRAM init fails | Wrong timing in SPL | Adjust dram_para in sys_config.fex |
For the A133, "firmware" usually means three distinct things: allwinner+a133+firmware+work