I guess timing is everything, as I just yesterday installed DD-WRT on my Archer C7 (v2, just like yours). I got hung up on a couple of little details (oversights on my part, actually). I, too was concerned about bricking the router but because I haven't been using it as a router for a while (but may soon) I decided to take the chance. As it turns out, there is a recovery process that seems to provide a reliable and simple (as long as you do it right) to always recover it (you need to download and use a ftp server program called tftpd32 or tftpd64).
The biggest confusing factor for me was which file, version, etc. to use. I ended up using the info described in a couple of threads on their forum. By far the best info came from this video on how to recover and flash TP-Link firmware. (most suggestions involve starting with an older version than what I had (I had the latest from 2018). The video involves flashing a C8, but the process is still the same. I used a laptop running windows 10 and a basic ethernet cable connected to one of the LAN ports. Video of the TP-Link recovery or firmware install procedure. BTW: My hangup ended up being a stupid failure to select the log view tab - the software used doesn't do a good job of highlighting the selected tab.
Once you have a desired or suggested firmware installed, you have to flash a file called "factory-to-ddrt.bin", which is done through the OEM GUI flash utility. Finally you flash the desired build of dd-wrt. It's confusing because the IP address of the router will change to a new value and I think you have to make sure you're connected to the WAN port to access it (I spent a couple of hours stuck at that juncture). After installing and upgrading to a version (they're all referred to as beta versions!) I set it up and it's working fine. Before I can put it in service as my main router, I'm going to have to educate myself on all of the settings (far more than the TP-Link stock setup). I settled on version 42557 (02/28/20) which appears to be running fine. BTW it seems that it's important to use the factory-to-ddrt.bin version that is in the same download location as the build you desire to use.
A post by Jeffs555 on this page really helped, as well as one by eginnc he referenced on this page.
The biggest confusing factor for me was which file, version, etc. to use. I ended up using the info described in a couple of threads on their forum. By far the best info came from this video on how to recover and flash TP-Link firmware. (most suggestions involve starting with an older version than what I had (I had the latest from 2018). The video involves flashing a C8, but the process is still the same. I used a laptop running windows 10 and a basic ethernet cable connected to one of the LAN ports. Video of the TP-Link recovery or firmware install procedure. BTW: My hangup ended up being a stupid failure to select the log view tab - the software used doesn't do a good job of highlighting the selected tab.
Once you have a desired or suggested firmware installed, you have to flash a file called "factory-to-ddrt.bin", which is done through the OEM GUI flash utility. Finally you flash the desired build of dd-wrt. It's confusing because the IP address of the router will change to a new value and I think you have to make sure you're connected to the WAN port to access it (I spent a couple of hours stuck at that juncture). After installing and upgrading to a version (they're all referred to as beta versions!) I set it up and it's working fine. Before I can put it in service as my main router, I'm going to have to educate myself on all of the settings (far more than the TP-Link stock setup). I settled on version 42557 (02/28/20) which appears to be running fine. BTW it seems that it's important to use the factory-to-ddrt.bin version that is in the same download location as the build you desire to use.
A post by Jeffs555 on this page really helped, as well as one by eginnc he referenced on this page.