iPhone 6 touch no working

Was there any obvious corrosion around one of the IC's that would lead you to believe that one or other was more likely to be bad? Was there a lot of corrosion near the LCD/Digitizer FPC connectors? Sometimes the whereabouts of the corrosion can give you clues as to what part of the board to focus on first.

Otherwise, I would start at the "end" of the circuit and work my way back before swapping out IC's. Remember that changing IC's requires massive amounts of heat; there's always a risk of secondary damage.

• Check the Digitizer and LCD FPC connectors on both the logic board and the screen. Some times there is a pin or two that get so corroded they do not make electrical contact anymore.
• The check the filters and capacitors on LCM_TO_AP_HIFA_BSYNC_CONN, TOUCH_TO_SAGE_VCM_IN_CONN, PP_SAGE_LX and PN_SAGE_TO_TOUCH_VCPL_FILT.
• Then check the voltage rails supplying the Touch circuitry PP5V1_GRAPE_VDDH, PP1V8_GRAPE, PN5V7_SAGE_AVDDN, PP5V7_SAGE_AVDDH and PP1V8

Once you have determined that there is no problems with the peripheral circuitry, I would start with Meson (Black) first, see if Touch returns and then try Cumulus (white).