if you have a saved copy of the mtd bins you can restore back to stock without opening..
Just need the kernel to contain mtd5,6 and 7..
cat ./mtd4.bin ./mtd5.bin ./mtd6.bin ./mtd7.bin > kernel
cp ./mtd8.bin rootfs
tftp the files as before ... Although press and hold reset before poweron(no need to wait till first led), hold reset until you see the kernel file requested in the tftpd logs..
done that many times now works fine..