You cannot flash firmware while the device is booted normally. It must be in MaskROM (firmware completely missing/corrupt) or Loader (functional bootloader present) mode.
Fixing the "RKDevTool No Devices Found" Error: A Complete Troubleshooting Guide
Use a pin or toothpick to press and hold the or Recovery button. While holding the button, plug the USB cable back in. Wait 2-3 seconds before releasing the button.
Troubleshooting "RKDevTool No Devices Found": The Ultimate Guide
Before diving into troubleshooting, you must understand the two distinct states RKDevTool uses to communicate with your hardware:
Remove the tweezers immediately after plugging it in. RKDevTool should read "Found One MASKROM Device". 3. Audit Your USB Cables and Ports
If your device is sitting on the Android boot animation or a Linux terminal, RKDevTool will read Step 1: Install and Verify Rockchip USB Drivers
Some Rockchip boards (like the RK3399 or RK3588 series) draw more power than a standard USB port can provide.
Avoid USB 3.0 (blue) or USB 3.1 ports if you encounter errors. RKDevTool often communicates more reliably using older USB 2.0 (black) ports driven directly by the motherboard chipset.
Click the button first to clear out any old, corrupted, or conflicting drivers.