I repair a lot of these gaming handhelds, ROG Allys especially. I wanted to highlight the most common hardware failure I see on these in case you find yourself in a similar situation as my customer here.
If you find your Ally X throwing a “hot USB port” error, inconsistent charging, or no power after letting the battery drain fully then it’s likely your unit has this issue. One, two, or more of these charge circuit related MOSFETs fail internally in a way that cause these problems. It’s simple enough to diagnose and fix.
Pic 1: These are typically the components I see typically go. Sometimes it’s all 4, just 1, maybe 2, etc.
Pic 2: My customer’s repair ticket. Gives some context behind what led up to the issue.
Pic 3: a thermal cam POV, an easy way to diagnose is seeing if the FET produces a significant heat signature. You can also use your fingers (ouch) or spray some isopropyl alcohol (91% or higher).
Pic 4: DMM testing. Another more accessible way to test is just to see if you have a continuous or near continuous path between the MOSFETs drain and source. That 0.003 reading is indicative of a faulty chip.
Pic 5: Just a photo of my replacing the components.
Pic 6: With the 65W charger connected and powering on the device we can see that the MOSFETs are no longer generating a heat signature indicating an internal fault. Off camera I also see that the ammeter is showing a steady high charge current.
Feel free to reach out with any questions! I made a short video showcasing this particular repair if you’re interested:
https://youtube.com/shorts/qRNQ84BXxGk?is=NGT9sr1xlswU5RTU