How To Fix iPhone 13 Pro No Power or No IMEI After Backglass Repair

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How To Fix iPhone 13 Pro No Power or No IMEI After Backglass Repair
Device	iPhone 13 Pro, iPhone 13 Pro Max
Affects part(s)	Main Logic Board
Needs equipment	Hot Air Station, Soldering Iron, Replacement Chip, iPhone Board Preheater, Reballing Stencil, Middle Layer Reballing Stencils
Difficulty	◉◉◉◉ Specialist
Type	Soldering

Problem description

After back-glass replacement, the device may show:

• No IMEI
• No modem firmware
• No cellular service
• Device completely dead (no power)

This increasingly common failure happens when shops use back-glass cracking tool on the baseband zone of the sandwich logic board.

iPhone 13 Pro/Max BB_PMU Location

Symptoms

• “No IMEI” in Settings > General > About
• “Modem Firmware: N/A”
• High current jump on DCPS
• If the device has been restored with baseband issues, you will have to restore it again after fixing the baseband issue
• If the phone is not wiped, do not restore it. Only perform an update. Restoring may result in the device getting stuck on the Hello/activation screen

• 

  iPhone 13 Pro/Max BB_PMU Location on BoardView

  Full dead device

Solution

Diagnostic Steps

1. Visual Inspection

• Inspect lower board under microscope
• Look for:
  • Hairline cracks on BB_PMU
  • Dent in the board from the backglass punch tool

(This is extremely common on iPhone 13 Pro / 14 Pro and Pro Max due to PMU location being very close to the back glass.)

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2. Software Diagnostics

If phone still powers on:

• *#06# → No IMEI
• Settings → Modem Firmware = N/A

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Example of blank modem firmware in Settings -> About

3. DC Power Supply Test

• Connect lower board only
• Press power:
  • High Boot Current jump -> Short

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4. Short Check

• Check around BB_PMU for shorts

Example of NO IMEI after restoring the iPhone

Repair Steps

1. Split the Logic Board (Sandwich Board Separation)

• Preheat to ~160–180°C
• Insert thin blades to separate upper & lower board

2. Remove the Cracked BB_PMU

• Clean Underfill around BB_PMU (Be careful of components around BB_PMU)
• Apply flux
• Carefully lift BB_PMU
• Inspect for damaged pads
• Clean with wick + fresh solder

3. Prepare & Reball New BB_PMU

• Use correct stencil for the model
• Inspect ball alignment carefully under microscope

4. Install New BB_PMU

• Align orientation markers correctly
• Reflow until IC self-centers
• Allow cooldown
• Clean board and inspect joints

5. Reconnect Upper & Lower Boards

• Align contacts
• Inspect under microscope for proper seam contact

6. Final Testing

• Connect to DCPS → verify normal boot current
• Boot device:
  • IMEI should appear
  • “Modem Firmware” should show correct version
• Test cellular, Wi-Fi calling, and SIM detection