Quick note — Totally agree with your steps and reasoning. Blinking usually means the charger sees a fault or a pack that is too low, and swapping in a known good battery is the fastest way to separate charger from battery without guesswork. The quick reseat trick is a safe last try, and avoiding jump-start hacks with lithium packs is the right call. That kit fits your situation because it gives you a fresh battery and a matching charger in one shot, so you can immediately test which piece in your current setup failed and still get back to work.
