Technical FPS on? Battery dead?

[JohnTheSmith]

So I went to go for a drive after just a day of being parked up. Try turn over, not a peep from the starter and dash lights barely light up. All the electrical stuff in the car basically aren't working as they should. No stress, must've left my stereo on by accident or sumat, that's why I carry a jump pack JIC. I slap that on, dash lights become a bit brighter but this time I get a very annoying "FPS ON" on the dash. Still, starter isn't making a peep. Instead the cars making a ticking, possibly a relay, noise. I find the cut off button under the dash but it feels like nothings happened to it, I'm *assuming* when it activates from a collision it believes happens, it springs up so you can press it back down. But it's already down, and the FPS ON is STILL there. I read in another thread that the light could show up from a dead battery, which tracks with the electrics basically not working. But my problem is the jump pack ain't doing the job and I'm halfway across the country from my house. Ive not had problems with my battery recently so I doubt it's completely died that quickly even with a radio on. Any advice?