Flashing, backups and IMEI: bootloop, Null IMEI and EFS
Most post-flash problems can be prevented with preparation: a backup, the right cable and a version check. This page collects guides on preparation and on what to do when a phone is stuck in a bootloop or has lost its IMEI.
Preparation is half the job
Before writing anything, make a backup: why an EFS backup matters and a firmware backup. Check the cable and USB port and the firmware version and patch.
If something goes wrong
- The phone will not boot: bootloop after flashing.
- No signal and no IMEI: Null IMEI, then how to restore the IMEI.
- MediaTek: NVRAM errors and recovery.
Restore the original IMEI only on your own device and within the law: restoring means returning the original number, not replacing it.
All guides in this topic
EFS backup: why you should make one before any work
What the EFS partition stores, why an EFS backup protects IMEI and network data, and how to make one before flashing or repair.
November 4, 2026 · 4 min readDriversCable and USB port for flashing: half the success
Why a phone is not detected in service mode because of the cable or port. Data cable, USB 2.0 vs 3.0, hubs, front ports and EDL cable explained.
November 4, 2026 · 4 min readDriversFirmware backup before service: protect the phone and the IMEI
Why back up before flashing and FRP: flash read-back, partition backups, EFS/NV and IMEI. How not to lose signal and the phone data.
November 4, 2026 · 4 min readDriversDeep Flash Cable (EDL cable): principle, use and limits
A Deep Flash Cable puts some Qualcomm phones into EDL 9008 by shorting pins. How it works, which models it suits, and when a test point is needed instead.
November 4, 2026 · 4 min readUnlockToolHow to find the firmware version, BIT and patch before work
Where to read the Android version, firmware, BIT and security patch before FRP and flashing. Download Mode, settings and Fastboot, and why it matters.
November 4, 2026 · 5 min readServiceBootloop after flashing: diagnosis and safe next steps
Phone reboot loop after flashing: how to separate causes, what to check first and how to recover safely.
November 4, 2026 · 4 min readServiceNull IMEI after flashing: causes and lawful restore
IMEI shows null after flashing: why NVRAM/EFS damage happens, why foreign IMEI is illegal, and how to restore this device lawfully.
November 4, 2026 · 4 min readMediaTekMediaTek NVRAM: errors, backup and lawful restore
MediaTek NVRAM errors: why calibrations and IMEI vanish, how NVRAM differs from EFS talk, and how to restore lawfully from this device backup.
November 4, 2026 · 4 min readServiceIMEI repair after flashing: tools and the rules that matter
Restoring the original IMEI after a bad flash: EFS and NVRAM backups, which tools support IMEI and baseband repair, and what to check first.
November 4, 2026 · 1 min readGuidesAll guidesHow-tos, error fixes and tool comparisons.Open the guidesOther topics
Drivers & modes · Android Multi Tool · UnlockTool · Xiaomi · Samsung · MediaTek · FRP · Software rental · TSM & TFM
FAQ
Why make an EFS backup?
On some platforms EFS holds radio data and the IMEI. Without a backup they can be hard to restore.
What should I do about a bootloop after flashing?
Check that the firmware matches the exact model and region, then rewrite the system partitions. The step-by-step order is in the guide.
Why did my IMEI disappear?
Usually the NVRAM or EFS partitions were damaged during the write. A backup or a service operation restores it.
Not sure which tool fits your model? Ask a technician on Telegram.