Image Check failed - installing a modified OpenWrt image (Atheros CSI tool)

I have a TL-WDR4300 v1.7 (not Israel) router with the latest version of OpenWrt firmware. Now I need to reflash the device with a modified firmware image. This is got from:
This modified version allows the Atheros CSI tool to send and receive Channel State information. However when I try to flash the device with this image, the Image check fails. I understand that if you try to downgrade, this fail is expected. However, I'm still worried to force the upgrade as it could potentially brick the router. Should I go ahead and force the upgrade?

Have you already asked this question to the author of the firmware image?

Yes, I don't get very many replies. I have seen the process of de bricking the router via a TFTP server. So in the worst case, if it does get bricked, I can recover it using this method right?

I have now forced the upgrade (downgrade). The router can no longer connect to However, judging by the lights on the router, it does not seem to be bricked:

solid power light
soild star
solid lan connection light when connected to computer

Looks like I'm going to have to use the TFTP method.
Does this router seem bricked? The computer shows a wired connection but just can seem to access the login page.