rkdeveloptool "Download boot failed!" in MaskROM: Causes and Fix

Symptoms

rkdeveloptool db loader.bin prints "Download boot failed!"
Board is visible in rkdeveloptool ld

Common causes

Loader built for a different SoC (e.g. an RK3568 loader on RK3588)
Device is in Loader mode, not MaskROM. db is only needed (and only works) in MaskROM
Corrupt / truncated loader file
USB hub or long cable causing transfer errors

How to fix it

Check the mode
If ld says "Loader", skip db and write directly. db is only for MaskROM.
```
rkdeveloptool ld
# DevNo=1 Vid=0x2207,Pid=0x350b,LocationID=... Maskrom
```
Use the loader for your exact SoC
Match the PID to the SoC family (350b = RK3588/RK3588S, 350a = RK3568/RK3566, 330c = RK3399) and use the matching *_spl_loader_*.bin from rkbin or your board vendor.
Connect directly and power properly
Use a short data cable on a rear/root USB port, and a real power supply for RK3588-class boards, then power-cycle into MaskROM and retry.

Go deeper

FAQ

What does "Download boot failed!" mean?

The loader you sent with rkdeveloptool db could not be downloaded or started by the BootROM. Usually it is the wrong loader for the SoC, or the device is no longer in MaskROM.

What causes "Download boot failed!"?

Loader built for a different SoC (e.g. an RK3568 loader on RK3588); Device is in Loader mode, not MaskROM. db is only needed (and only works) in MaskROM; Corrupt / truncated loader file; USB hub or long cable causing transfer errors.

How do I fix "Download boot failed!"?

1. Check the mode: If ld says "Loader", skip db and write directly. db is only for MaskROM. 2. Use the loader for your exact SoC: Match the PID to the SoC family (350b = RK3588/RK3588S, 350a = RK3568/RK3566, 330c = RK3399) and use the matching *_spl_loader_*.bin from rkbin or your board vendor. 3. Connect directly and power properly: Use a short data cable on a rear/root USB port, and a real power supply for RK3588-class boards, then power-cycle into MaskROM and retry.