یکبار دستگاه رو فلش کنید.نبودن تصویر چندین علت داره.یکی اینکه ای سی سازنده ولتهای مهم در ادرس مشکلی رو حس کنه که پروتکت کنه.یا خودش خراب باشه .یا توسط برد مین فعال نشه
when vds supply is booted on main board it reaches the scaler pcb and after it reaches boost chip which is also buck convertor will generate 3.3 volts which is vcc of panel mcu, if panel mcu is booting up properly it will send en pulse which is around 3.3 volts (en is on off of boost chip), once en reaches the first thing is that Avdod will be generated around 15 to 17 volts if we speak about cm501 ic the pwm which is needed to drive avdd is internal, once avdd is ok it is again converted in to half which is havdd or vcom if avdd is 15 volts the havdd will be exactly half of avdd which is 7.5 volts, avdd is again used towards vgh using doubler circuit and vgh is developed as well vgl is also developed, so for no boost you need to check the above voltage chart, cold test is very good method when there is no boost, you need to always use very high quality multi meters, keep your multi meter in highest ohms range and check resistance between ground and vgh it should be in kohms, you need to check resistance between ground and vgl which should also show high ohms you need to check avdd and havdd which again should show high ohms, you need to check resistance between vgh and vgl which should show high ohms again, please note in the above test point if anyone of the above i.e vgh, vgl, avdd, havdd is showing low ohms will push the boost ic to go into protection mode and there will be no outputs in such case, so please refer to the above mentioned methods it is very important and helpful