Trouble Shooting; Fail To Startup/Power On - Blu Dash 4.5 Service Manual

3. Trouble Shooting

3.1 Fail to startup/power on

The following conditions may cause boot fail: battery low, battery connector is damaged or
bad welding, components bad weld/short-circuit or damaged
First, change a fully charged battery test, still startup fail, check battery connector ok or not,
if connector damaged change a new one;
Second, connect to DC power supply, if the boot process is no current, we should check
power key solder ok or not;
Third, if the boot current is very small and cannot maintain ,connect the power on test point
to GND, then check below voltage in sequence, VPROC_PMU，VCORE_PMU，VM_PMU，
VRF18_PMU，VIO18_PMU，VIO28_PMU，VEMC_3V3_PMU，VEMC_1V8_PMU ok not.
Fourth, if the current stay in 40mA, we should check the circuit around flash, when CPU
calling program from flash fail, the current will stay in 40mA, re-download the software or
change a new flash or CPU.
Fail to power on
Check if the battery
is OK.
Y
Check if battery
connects solder ok
Y
Is power key OK?
Y
Check each power
out of PMU
Y
Re-download
Software
N
Resold or replace
U1082
N
Resold or replace
U300
N
Change
battery
N
Resold
connect
N Change a new
power key
N Re-solder or
replace U2
Y
OK
Y
OK
Y
OK