What Is a Test Point

A test point is a designated exposed copper pad or via on a printed circuit board (PCB) that gives technicians direct electrical access to critical hardware signals. On the OPPO A3S CPH1803, these pads are used to force the Qualcomm Snapdragon 450 chipset into Qualcomm Emergency Download Mode (EDL / 9008 mode), bypassing the normal boot sequence. This is essential when standard software tools or the device's own bootloader can no longer facilitate firmware operations, making test points a fundamental resource in professional mobile repair workflows.

When Technicians Use This Method

Test point access on the CPH1803 is typically required in the following scenarios:

  • Dead Boot Recovery: The device powers on but fails to boot, showing a black screen or bootloop after a failed firmware flash.
  • FRP (Factory Reset Protection) Bypass: The device is locked to a Google account and conventional ADB or menu-based bypass methods have failed.
  • IMEI Repair: The baseband or IMEI has been corrupted and must be restored at the partition level.
  • Firmware Flashing: Official recovery or fastboot flashing is inaccessible due to a corrupted bootloader or locked device state.
  • Pattern / PIN Lock Removal: Security credential data must be wiped directly via EDL when the device cannot enter recovery mode.

Locating the Test Point

On the OPPO A3S CPH1803, the EDL test point is located on the back side of the main PCB. After removing the rear cover and battery, disconnect the battery connector and carefully lift out the motherboard. The key test point pad used to trigger EDL mode is a small exposed via situated near the edge of the board, close to the eMMC or CPU cluster. This pad must be shorted to ground (GND) while connecting the USB cable. Exact silkscreen labeling is absent on most units; technicians should reference a verified CPH1803 PCB diagram to confirm the precise pad before proceeding.

Step-by-Step Access Procedure

Follow these steps carefully to enter EDL mode via the test point:

  • Power off the device completely and remove the SIM tray.
  • Open the rear housing and disconnect the battery from the motherboard.
  • Remove the motherboard and identify the EDL test point pad on the PCB back side.
  • Using a conductive wire or precision tweezers, bridge the test point pad to the nearest GND pad.
  • While holding the short, connect the device to a PC via USB cable.
  • Check Device Manager (Windows) for a new Qualcomm HS-USB QDLoader 9008 port — this confirms EDL mode is active.
  • Release the short once the port is detected and launch your flashing tool (QFIL, MRT, or similar).
  • Load the appropriate firmware scatter or rawprogram files and execute the desired operation.

Safety Tips and Precautions

Incorrect test point procedures can permanently damage the CPH1803. Observe the following precautions:

  • Always disconnect the battery before shorting any PCB pad to prevent power surges.
  • Use only quality USB cables rated for data transfer — charge-only cables will not establish a 9008 port.
  • Confirm chipset compatibility: only use Qualcomm-specific EDL tools for the Snapdragon 450 platform.
  • Do not apply voltage to test point pads — only establish a ground short as directed.
  • Work on an anti-static mat and use an ESD wrist strap to prevent electrostatic discharge damage.
  • Verify firmware package authenticity before flashing to avoid introducing new boot errors.

Pin / Test Point Reference

PinDescription
EDL Test Point (TP_EDL)Short this pad to GND while connecting USB to force Qualcomm 9008 EDL mode — Located on PCB back side near eMMC/CPU area; confirm with CPH1803 board diagram before use
GNDGround reference pad used as the short target for EDL activation — Any confirmed GND via adjacent to the EDL pad may be used

Tools required: QFIL (Qualcomm Flash Image Loader), MRT Dongle, UMT Pro / Ultimate Multi Tool, Medusa Pro Box, EasyJTAG Plus, Conductive tweezers or fine wire, Anti-static mat and ESD wrist strap, Quality USB data cable, Qualcomm 9008 USB drivers (Windows)

Supported operations: FRP Erase, Dead Boot Repair, Firmware Flashing, IMEI Repair, Pattern / PIN Lock Removal, Full Backup / Read Firmware, Bootloader Repair

âš  Safety note: Disconnect battery before shorting pads. Use ESD protection. Never apply external voltage to test points. Use only verified CPH1803 firmware to avoid permanent brick.