Damn, if only you weren’t so hell bent on investigating and just blindly accepted the existence of ghosts. Then your haunting would be real.

As a low-voltage service tech, I can tell you a ton of stories like this. It's always something simple that gets overlooked.

I have very bright outdoor sensor lights. Ghosts often set them off, saw on once. furry. long tail, crawling under the fence disguised as the cat down the road.

My ghost steals socks out of the dryer.

Used to have random voices in my house, late at night when I was sitting quietly at the computer. First time it was rather shocking, just a few words, softly eminating from the computer speakers in a man's voice while I was doing nothing on the computer that should bring up sound.
Second time it happened, I caught on. No ghosts. I live on a highway, trucks go by all the time. If the trucker happened to key their CB just as they went by it would somehow bleed over into my computer and broadcast out through the speakers.
I have a different computer now and switched to wifi. Presumably one of those resulted in a lose of that "connection" as I no longer pick up the late night comments.

Not ghosts, but electric or magnetic or radio frequenmcy fluctuations . The new lights are ultra sensitive and will pick up these fluctuations and react accordingly.

I was a chef at a club and my litvhen was just behind the bar and the girls would come in and out grabbing supplies and beer out of the fridge. the said somhow the fridge door was always open and they were so sure it was a ghost and were surprised I was not scared to work thwre alone. so one time this girl come in and grabs a couple of beers, slams the fridge door shut and the damn door bounces and slowly opena back up and stays that way. I couldnt help laughing at them. instead if enlightening them I kept telling thwm I would hear weird stuff when it was closing time lol

Mine blink too... low batteries the problem... I hear ya.

Another possibility.....spiders crawling across the sensor

My house alarm went through a phase of going off randomly in the middle of the night. When I finally got to the bottom of it, the world's tiniest spider had set up home inside of one of the PIR sensors.

PIR's function off infrared light. Basically two sensors (focused through a lens) and subtracting one sensor light level input from the other. If the difference changes significantly (a warm blooded creature being picked up by one sensor but not the other) the PIR activates a relay (turning on the light, triggering the alarm etc.) If something affects both sensors equally (a room warming up or cooling down) then it does not. Presumably my spider was blocking some of the IR to one of the sensors when it crawled in front of it.

Please demonstrate your evidence for the existence of ghosts. You should not assume the cause of unexplained phenomena is the result of supernatural forces. Isn't that the cruxt of religion?

You really don't.
Call an electrician.

The ghosts of dead batteries.

I was kinda hoping this would go somewhere I could sink my teeth into. Love this stuff, but you disappointed with with the ending lol

I'm not sure I believe in ghosts but here goes with my little story. Was living in New Orleans in a very old, old shotgun style house. Went to bed one night and because it was Nawlin's it was hot and muggy, so I removed my red dress that I had on and threw it on the floor, inside out. I woke up the next morning fully dressed in my red dress, right side out, on my back (I never sleep on my back it gives me nightmares!!!) with my hands/arms crossed at the wrists, resting on my chest. I am not prone to sleepwalking and have no memory of getting up and dressing myself. Also, experienced flying objects in the bathroom, also witnessed by my daughter and a misplaced credit card eventually found in a place that I would never have placed it. !!!! Just sayin'! In my defense to all the 'judgies' out there, I will say that I'm really quite sane but of course you only have my word for that!

It's probably the breeze generated from your heating and cooling unts.

Salt also gets them to go.

I do IT work for one of those old plantations. The staff is convinced their are ghost. I tell them to let me know if they see a ghost. I will run over to it. I'll do what ever I have to. Make fun of it's like, insult their mom. Whatever. But so far as of this report, ghost seem to be afraid of skeptics.

This is a great Ted Talk about the scientific approach to the paranormal. Spoiller alert: Like the OP (@jules4169), It starts by "believing in ghost" (wink wink) to finding the real explanation.
[ted.com]

People say the restaurant I work in is haunted. Yeah right!

I had a possessed tv once. I was home alone playing on my brother's Gameboy when the tv turned on. Thought it was my dad playing a trick on me, but there were the remotes sitting right there on the table nearby. As I was pondering this, it turned itself off. I shrugged and went back to my game boy, but then it turned back on again! And then it turned off! And then it turned on again! I was like... WTF... So I went in the kitchen while it was still on, eventually it turned itself off. I think it was a battery problem too, but soon after we got a new TV so it went away.

Have you seen a mental health professional that can prescribe you anti psychotic medifation?

Thanks for sharing that...I did not know it.

I was waiting to hear that you had ... intruder kitties.