download putty when you have windows, then go to device manager at windows when you connected the usb from uart to the pc and find out the com port number. open putty and select serial, change the com1 to the port number you saw at device manager. then delete 9600 and write 152000 then you start it. start controller then it will show you the u-boot 1.1.4 text. press as fast as possible the key ESC to stop the autoboot otherwise it will stuck at could not find rcS file. Then execute the command:
setenv bootargs board=DJI-WM305 console=ttyS0,115200 root=/dev/mtdblock5 init=/sbin/init mtdparts=ath-nor0:256k@0k(u-boot),64k@256k(u-boot-env),896k@320k(kernel1),3008k@1216k(rootfs1),896k@4224k(kernel2),3008k@5120k(rootfs2),64k@8128k(art),3904k@320k(firmware1),3904k@4224k(firmware2),8192k@0k(all)
bootm 0x9f420000
mkdir /tmp/flash
mount -t jffs2 mtd3 /tmp/flash
then you can go and fix the rcS file via ftp. Use filezilla and select the ascii mode. Use notepad++ to edit the file rcS.
After editing, right click on rcS file at ftp and select permissions or so. In the lower middle field it should say chmod and there is number or so I do not remember. Change the number to 775 and save it. This will fix the error: could not find rcS file.
