Power supply issue

I'm using a pro mini to operate an LCD, USsensor, and a few LED's.

anyway, all of a sudden it wouldn't take Batt voltage anymore, I checked my connections (all solid) tried new batteries, even held a new battery directly to the GND and RAW where original power is hooked up. (I'm using a 9v) and still nothing.

it only turns on when I attach the FTDI so my question is WTF!?

I even checked the smoke level and its still full.....

With 9V connected to RAW & Gnd, you are not seeing 3.3V or 5V at the VCC pin?
Perhaps the onboard voltage regulator got damaged.

Is your battery dead?

NO voltage at VCC when GRD and RAW are connected to 9v

I guess the VR did go bad, but there is no obvious sign of damage to the board at all.

how often do they just stop working??? like I said I'm not pushing a huge electrical demand on this project.

any suggestions for adding a new VR circuit and attaching it to the VCC?

I really don't want to undo all the soldering to replace the board.

If you can't be arsed to unsolder, your other option is to give the board 5v on vcc.

External 7805
https://www.digikey.com/product-detail/en/on-semiconductor/MC7805CTG/MC7805CTGOS-ND/919333
Datasheet says no external caps are needed, unless there are long wires involved.
I would add 10uF on the input and 1uF on the output, maybe overkill but certainly won't hurt.
https://www.digikey.com/product-detail/en/wurth-electronics-inc/860020672005/732-8851-1-ND/5728796
https://www.digikey.com/product-detail/en/wurth-electronics-inc/860010472002/732-8625-1-ND/5728581

I was also think of using a buck converter. any thoughts on that???

at a later date I might add more to the project and I hear that they bucks are more efficient and rob less power.

That would be one way to do what I said. Is your 9v source non-negotiable? 5v power supplies are dirt cheap. If you're needing a battery solution, you're better off ditching those small 9v anyway. Find a USB powerbank.

it doesn't have to be 9v but battery power is a must.

the project is a sensor I use for my tip bucket when I play a gig.

the LCD prints some things and when money or what not passes the US sensor then it prints thank you so I don't have to stop singing

Perhaps there was a reason the Vr went belly up. Any possibilities of a short? How long was the project working before it stopped?

I checked for shorts and I didn't see any.

there is no "over heating" signs on the board or VR.

usually when something like that goes out you'll definitely smell it.

there was no smoke or anything.

for now I'm going to diagnose it as cheaply made knock off.... it is not Arduino brand.

I'm going to just add an external VR and leave it at that. if I have further problems after that then i'll dive deeper into it

LEDs have resistors?

always.... I put a 270 on it

at the moment there is only one on the project. I use it to show when the sensor is within the range I set.

(its on the back side of my project. so only I can see it, it just lets me know its working)