My nikon sb-800 flash keeps firing off by itself?

When i take pictures, the flash still works with my d90. The buttons and the lcd is fine. The problem is, when i turn on the flash (whether it's on my camera or off of it) after a few seconds, it flashes. Then another time after a few seconds. Then another time until the flash goes on standby. When it's on standby, it doesn't flash. But when i turn it on again to use it it flashes by itself again. It wastes the power and it could blind either me or my subjects. Please let me know if there's any way i could fix this.

While I initially wanted to conclude there's a problem in the connection between the contacts and the hotshoe (ant to get both cleaned). I have a feeling that in not the case. On my D200, hotshoe is worn so it randomly fires my sb900 when mounted. It may be a wiring issue or dirty battery contacts too as it is having a power issue. Also check to see if a piece of dirt is trapped in the test button…

i am using a SB 800 and lately this problem of the flash firing every few seconds has started happening

No answers that hone in on the exact cause? One of my SB-800 decided to randomly do the same thing. On camera and off camera holding it in my hand. Had it on a D700. Also, tried it on my D750. Same problem. The idea that it misfires OFF either body tells me the issue is with the flash unit itself. The battery contacts are clean. The flash is always kept in its bag, so, I doubt there is dirt in the test switch - but I will look anyway - and will press it multiple times to maybe clean it out if something is there. Was hoping for a technically specific answer.

Same problem for me. Still can't find a solution online.