You will need a Canon service tool of version 5204 or later (higher version number). The use of a service tool that is too old (too low version number) will cause loss of access to service mode. It seems you will have to buy the tool from Ebay or similar. I think downloading a free tool from the web is risky if you find one. I found a few sites but Malwarebytes Browser Guard blocked access to the sites.
For an instruction for entering service mode and doing the reset see this post. The instruction is for an older service tool v 4718, but the procedure is the same.
Actually just checked and the WICReset app also supports the TS5000 series so it should be able to do what you need as an alternative to the Canon service tool. You'll need to purchase a WICReset key though.
The instructions @PeterBJ provided for getting it into service mode still apply though.