Input voltage drop

[adr]

(Pretty sure I'm dealing with a legitimate board - see attached photos)

I completed soldering all the components and verified all are in the right locations. I have a 9v battery wired up with a center post positive barrel connector. The charge on the battery is actually closer to 8v. Before connecting the barrel to the DSO138, I measured the voltage across the barrel's center and the exterior and confirmed that it is 8v. When I connect the battery/barrel to the DSO138 and I measure the voltage at the barrel's input terminal, it starts out at 8v and steadily drops to 4v where it stabilizes. Voltage at J9 also gets to 4v and voltages around the board are correspondingly low - the voltage at T22 is extremely low. When I disconnect the battery and measure its voltage, it is 8v as it was prior to connecting it.

Could there be something loading the input voltage to the point where it drops the input to such a low level when it is connected to the board?

JP3 is shorted. JP4 is open

Photos attached.

[MNTech]

Have you considered trying a new battery?
A fresh 9 Volt battery should measure about 9.6 Volts with no load.

[adr]

A fresh battery did indeed help. I'm now getting TP22 = 3.3v and +5v at V+.

Not sure why a fresh battery would be needed b/c even a fresh one will become unfresh like the original I tried but I'll go with this and start taking the next step (ie. short JP4).

Thanks for the guidance.