After upgrading the ROM of HP hx4700 from WM 2003 to WM 5.0 (official ROM) there arose some problem to boot to system. The screen shows just “Serial” in the upper part of the screen and HP invent logo in the middle and 1.01 in the bottom part of the screen and that is all. No booting to system. I have tried almost all suggested methods. I bought even new battery. Nothing worked. Booting was still problem.

I observed that occasionally it was possible to wake the HP up after longer time of drained battery, but that was too long time to wait. Installing program that required restart reverted the state back to the frozen screen with “Serial” on the top. After plugging to USB on PC the “Serial” turned to “USB”. But no booting.

From the observed behavior there arose some procedure that works in my case. The procedure to wake up or revive the PDA is to wait till the battery is drained and then plug it to the charger for about 1 s. Then unplug it and plug it again. After few tries it hopefully starts with booting procedure.

If “Serial” appears I wait till it disappears and then repeat the procedure.  It looks like giving it some kind of heart electric shocks to revive. 🙂 I guess that there is some issue with the boot loader because the WM 5.0 is installed from the PC when the PDA managed to wake up and installation finished fine. Rebooting the PDA resulted to frozen bootloader screen.

So my state now is to have PDA without program that requires restart. Combining with the new battery with higher capacity (3600 mAh) the HP hx4700 can be in sleep mode for about 2-3 weeks.

Hope that this small reviving procedure will be useful for somebody else as well.

If not, try this links. There may be still some hope.

http://forum.brighthand.com/ipaq-hx4700-series/258061-hx4700-wont-boot-finish-clearing-data.html

http://forum.brighthand.com/ipaq-hx4700-series/226521-rel-hx4700-bootloader-tool.html

or the universal bootloader tool page on SourceForge:

http://en.sourceforge.jp/projects/sfnet_ubl/releases/

UPDATE:

Just recently after giving up all the hope for my HP to wake up and plan to dig out parts that can be used in some other “project” I found that it can boot quite normally. Showed screen with HP and 2.01 in bottom right hand side and booted to previous install.

Thought that it got scared of being dissected but maybe reason was that I took also small NiMH Varta battery out. This maybe the case because after another frozen bootloader screen when this battery was taken out the HP started normally. Then switch off, wait 10 s and insert small battery. For all that you need to open the device. Then the booting works fine.

Voltage of the NiMH battery is still 1.2 V as declared by producer (Varta), so I really do not know, what is the issue.