Low-voltage Christmas tree lights

Battery-powered Christmas tree lights bought at Intermarche for ~$4.
50 white LEDs are connected in parallel, battery holder for 3 AA cells contain also mechanical switch and resistor in series. LEDs seem to be pretty well matched, with no observable differences in emitted light.

When powered from 3 NiMH cells this draws ~60mA. When powered from 2 NiMH cells (one pair of battery contacts shorted) - about 2.5mA, with very low light intensity.
These lamps have nominal parameters specified as 3V/20mA, but it does not make much sense with battery holder for 3 cells.
I have to warn that this one was dead on arrival with cable not soldered to contact. Quality control might be not perfect, but it is still great value if you have soldering iron prepared.
As improvised power source I've used old Nokia charger (ACP-7E) with additional diode and 27Ohm resistor in series.

Fixing "The Application was Unable to Start Correctly (0xc000007b)" error

1. Check if executable is 32-bit or 64-bit.
2. Download http://www.dependencywalker.com of same type
3. Open executable in Dependency Walker. Most likely there would be error(s), but it is not important. The important thing is list of DLLs:

Look at the "CPU" column for red text - this is missing DLL. In this case - vcruntime140.dll, part of Visual C++ 2015-2019 runtime for x86. Missing VC++ runtime libraries are quite often, in general, depending on dll number:

"80" -> VC++ redist 2005

"90" -> VC++ redist 2008

"100" -> VC++ redist 2010

"110" -> VC++ redist 2012

"120" -> VC++ redist 2013

"140" -> VC++ redist 2015 (or 2015-2019)