Add a 0.1µF capacitor between the EN pin and GND, plus a 10kΩ resistor from EN to VIN. This creates an RC delay, preventing input inrush current.
Read the top marking. If it says "4015" → it is an XL4015. If "2596" → LM2596. If "5430" → TPS5430.
Assuming the common case of a (YP-05 as a PCB assembly), here’s what to look for on the schematic: