Follow this guide and upload the latest firmware for your device, and see if you get farther:

The latest firmware is this when uploading from uboot if you have NAND:

http://download.gl-inet.com.s3.amazonaws.com/firmware/ar300m/nand/v1/lede-ar300m-ubi-2.27.img

Or this if not:

http://download.gl-inet.com.s3.amazonaws.com/firmware/ar300m/v1/lede-ar300m-2.27.bin