My Controller Will Not Charge Any More And The Light Just Flashes

The fact that it works on a data cable is genuinely good news, because it tells us the mainboard and the controller itself are alive. The fault is isolated to the charging path, which is one of the cheaper and more approachable repairs on this hardware.

There are two likely causes and your symptom leans towards one of them. The flash-then-stop pattern typically means the charge circuit starts, checks the battery, and refuses to continue. Lithium cells that have dropped below a certain voltage, or that have degraded internally, get rejected by that check. This is extremely common on a DualShock 4 of any age, because the battery is small and gets charged daily. The second cause is the micro USB port itself: the data pins and the power pins are separate, and the data pins can keep working after the power pins have gone intermittent from the constant cable flexing that micro USB invites. You have ruled out cables and chargers already, which is exactly the right first step, so the fault is inside the controller.

For a student budget, this is good ground. A replacement DualShock 4 battery is a genuinely low-cost part, it is a plug-in connector rather than soldered, and it is one of the easiest controller repairs there is. Start there, because it is both cheaper and more likely than the port. If a new battery does not charge either, the port is next, and that one does need soldering, so a repair shop is reasonable at that point.

One safety point, and please take it seriously: if the battery is at all swollen, puffy, or has lifted the shell, stop and do not charge it again. Take it to a shop or a recycling point rather than handling it yourself.