Arduino Mega Clone CH340G Capacitor Values
The values can be easy found for generic CH340g and ATmega2560 implementations:
C1,C2 = 100nF, C3,C4 = 22pf but depends on the crystal you use, all others excepting C12 are decoupling capacitors.
C12 has no sense where it's placed, it seems that the schematic is a bad combination of schematics, this capacitor should reset the board at power on but it breaks the reset pulse from CH340g so you cannot program the board without pressing manually the reset pushbutton. Don't place C12 at all.
Also place a short instead of R5 and R6 that are not in the CH340g manual (there is a special mention to connect the pins straight to USB bus), remove R8, is not needed for the same reason, R3 makes no sense, don't place-it.
R2,R4 = 1K, R7,R9 = 10K, R10,R11,R12,R13 = 1K, R14 = 10K , R15 = 1M.
Y1 = 12Mhz, Y2 = 16Mhz
A 22 ohm resistor is missing in your schematic between Y2 XTAL1 and ATMEGA XTAL2 but I don't think it's important.
I hope I didn't missed something
The bare minimum is to remove c12 and maybe R3 and check the values you used for R2, R4 against the above values.
If something would be wrong with CH340g the USB connection would fail but I see no mention about that in your post.