It could very likely be a 3.3v regulator as the NEO-M8N chip requires a Vcc of 3.3v. (Is the board's input power 5v ?). You could also power up the board and measure pin 23 (Vcc) of the NEO-M8 chip, (on your board pin 24 is at the corner closest to the red dot, pin 23 is then to the right). Many other designs using the NEO-M8 chip use a similar low power 3.3v regulator (SOT-23-5) to step down from a 5v input.
If Vcc of the NEO-M8 has something lower than 3.3v then perhaps the regulator chip is the main problem, (but if it's 5v you might already have a blown out NEO-M8 chip).
Here is a pdf of a common 3.3v regulator from Micrel, (MIC5235), many similar low power 3.3v regulators have a similar pin out (though not guaranteed).
If you can trace out visually or with a ohm meter at least the Input, Output, and Ground pins on the small chip and they match the common regulator configuration you can be fairly sure it is a 3.3v regulator.