PW3 Problem with PW3 after serial port mod

[fonix232]

So, after having my old PW3 laying around unused for over a year now (bought the latest Oasis last year), I've decided to jailbreak it the hard way.

Soldering the pins went relatively straightforward - the hardest part was removing the front plate of the device without ruining the glue strips.

However since I've had the serial port wired up, for some reason the Kindle won't boot completely properly in regular mode. It starts up, but during the boot animation (the bar filling) the screensaver flickers in for a moment or two, before settling on it permanently. Through the serial port I can see it boots properly, and after doing the first step of the jailbreak (removing the root user password from the "regular" system partition), I can log in and play around. The device does not respond to the power button (apart from the 15 second long press to cut the battery), and after some time, sending data to the Kindle through the serial port also hangs. It is not frozen, since if I e.g. long press the power button until it reboots, or connect a power supply, I can see logs coming through - but entering any data is not possible.

At first I thought it's a hardware fault, however diag mode does not produce this effect. In diag mode, everything works as intended, the serial port does not freeze, and I do not get locked out at any point.

What could have gone wrong? I've literally didn't even touch the main OS partition at first, the only change that happened between it working and suddenly producing the above effect is the two pins being soldered to two freestanding (insulated) wires. They are not crossed - otherwise I wouldn't get any output through my adapter.

And what could be done? I was thinking about using the recovery mode that is prompted during boot, which offers to flash a *.bin file from internal storage. Since my PW3 is on a relatively old(ish) firmware - 5.12.1 if I recall correctly - I could flash a somewhat newer, but still not the latest firmware.

[eddie.t.h]

You probably had to break off the Hall sensor which is located on the LED strip. Your reader now thinks it's locked in a case.

[fonix232]

Isn't the hall sensor located *under* the LED strip? I haven't touched that part at all.

EDIT:

Okay, went through some disassembly photos of the PW3, and looks like in the attempt to solder the 1.8V line (which I ultimately dropped), I managed to solder over the small resistor at the FL/HALL connector. So little it's barely visible.



The one I'm talking about is just next to the connector's pin that is marked "2", under the last "L" of the "FL/HALL" mark. I'll clean that up and see where I can get with it.

[eddie.t.h]

The sensor is on the right side of the Led strip. It is such a tiny black rectangle. Right next to the spatula in the photo. A bit higher than a typical smd resistor. Sometimes it breaks off when the front bezel is not properly disassembled.

[fonix232]

Originally Posted by eddie.t.h

The sensor is on the right side of the Led strip. It is such a tiny black rectangle. Right next to the finger in the photo. A bit higher than a typical smd resistor. Sometimes it breaks off when the front bezel is not properly disassembled.

Yep, double checked, and the sensor is in place and not damaged. I'm still thinking it's my dumb ass soldering over that resistor at the connector. I'll clean that up today and try again.

[eddie.t.h]

You can check the sensor operation with the command:
cat /sys/devices/system/wario_hall/wario_hall0/hall_detect

0 - no magnet
1 - magnet detected

You can also disable the sensor by:

echo 0 > /sys/devices/system/wario_hall/wario_hall0/hall_enable


Good luck!

[fonix232]

Originally Posted by eddie.t.h

You can check the sensor operation with the command:
cat /sys/devices/system/wario_hall/wario_hall0/hall_detect

0 - no magnet
1 - magnet detected

You can also disable the sensor by:

echo 0 > /sys/devices/system/wario_hall/wario_hall0/hall_enable


Good luck!

Already cleaned off that bit of solder from the resistor, and now my PW3 works just fine. Thanks for pointing out what the core reason was, made finding the actual issue much easier!