Refurb bird is only $800. That's what you get from DJI anyway on a warranty claim. Then figure you've got a extra controller,battery and two sets of props.. seems cheaper than insurance.
My two cents. An interesting question, "does installing a third party software void a hardware warranty if the product fails?" The short answer is "yes". There are multiple cases of hardware warranty being denied after installation of third party software. This includes cases involving Apple computers and rooted cell phones.
The long answer is whether you can prove the third party software caused the problem.
As has been stated, without the drone that is near impossible to prove.
It would be worth stating in a clear and unambiguous notation on the DJI refresh site, that installation of the Litchi software will void the warranty.
At this point, it might be worth an attempt to file a complaint with the State Attorney General, consumer affairs. The complaint occurs where the sale occurred, which would be your state.
It is an online form. I have done it for a number of issues concerning warranty coverage and product failures. You would be amazed at how quickly a firm will respond and often "pay up" when the state attorney writes a letter.
There is no down side, it costs nothing. It is your tax dollars at work. Remember, the state attorney is paid by you and works for you.
Just my thoughts.