Check voltages of each group of power. The typical voltages for power nets are:
3V3: 3.3V1V8: 1.8VVDD-CORE: 0.9VLDOB-OUT: 1.2-1.3V in FEL mode, 1.8V in normal operation
Check whether there are bad electrical connections.
Check whether separate nets are accidently connected.
Check whether TX and RX signals are matched. Try interchanging them. Remove the boot media and connect the board to a computer via the otg port. If a new device is detected by the computer, it means the chip worked properly and you should check the boot media. Otherwise use an oscilloscope to check whether the crystal is oscillating. If not, check the power, and in worst cases the chip is probably dead.
Use a better power supply. Remove the load capacitors of 24M crystal (C13, C14). If the problem is eliminated it indicates the value of load capacitors was too large.
Check the soldering of the card slot. Use a better card as bad blocks can cause failure.
If the backlight is not up, check the boost circuit. Otherwise check the level of DISP signal. It should be pulled high for most panels i.e. R32 should be soldered.