The Digma Citi Z540 4G is an ultra-budget smartphone from 2016, designed by the Russian brand Digma for essential 4G connectivity. It features a compact 5.0-inch display and is powered by a UNISOC (Spreadtrum) processor. Due to its very basic hardware, the device is prone to performance degradation over time. This guide provides the official stock ROM (.pac file), which is the most effective way to unbrick the device, fix software bugs, resolve bootloop issues, or remove a Google FRP lock. Important: This firmware is specifically for the Digma Citi Z540 4G. As a UNISOC/Spreadtrum device, it requires the SPD Upgrade Tool for flashing. Flashing this on a different model will cause a hard brick. This process will erase all data.
Quick Device Specs
- Device: Digma Citi Z540 4G
- Release year: 2016
- Chipset: UNISOC SC9832
- Display: 5.0″ IPS LCD
- Battery: 2000 mAh
- Original OS: Android 5.1 (Lollipop)
Required Downloads
To flash a Spreadtrum/UNISOC device, you will need the specific drivers and flashing tool. You can find the downloads for these in our main guide linked below.
- SPD Upgrade Tool or SPD Research Tool
- Spreadtrum/UNISOC USB Drivers
Stock ROM (Firmware)
| Build Date | Android | Type | Download | Chipset |
|---|---|---|---|---|
| 2016-10-26 | 5.1 | SPD .pac Firmware |
Download | UNISOC/SPD |
How to Flash the Stock Firmware
Flashing the stock ROM onto your Digma Citi Z540 requires a Windows PC and the SPD Upgrade Tool. Here are the key steps:
- Install the correct UNISOC/Spreadtrum USB drivers on your PC.
- Launch the SPD Upgrade Tool and load the downloaded
.pacfirmware file. - Power off your phone completely.
- Click “Start” in the tool, then connect your phone while holding the Volume Down button to begin flashing.
For detailed, step-by-step instructions with screenshots and tool download links, please follow our comprehensive pillar guide: How to Use the SPD Upgrade Tool to Flash Your Smartphone.
Device-Specific Troubleshooting for Digma Citi Z540
- Driver Installation Fails on Windows 10/11: The most common failure point is incorrect drivers. The SPD Upgrade Tool will not see your phone if the drivers aren’t installed correctly. You must install the Spreadtrum VCOM drivers, which often requires you to disable ‘Driver Signature Enforcement’ in Windows before the installation will succeed.
- Fixing “Insufficient Storage” Errors: With only 8GB of internal storage, this device constantly runs out of space. A clean flash of the stock ROM is the best way to clear all junk files and free up the maximum possible space, which can temporarily solve this issue.
- Resolving Google Play Store Crashes: If Google Play Store or Google Play Services are constantly crashing, this is a sign of software corruption. Flashing this stock ROM will completely reinstall a clean version of the operating system and all core Google apps, resolving these crashes.
FAQs
Q1. What is Digma?
Digma is a Russian brand that sells a wide range of consumer electronics, including smartphones, tablets, and e-readers, primarily targeting the budget-friendly market segment in Russia and neighboring countries.
Q2. Can I upgrade this phone to a newer Android version like Marshmallow or Nougat?
No. This device’s official support ended with Android 5.1 Lollipop. Due to its basic hardware and regional focus, a custom ROM community for it is virtually non-existent, so no unofficial upgrades are available either.
Q3. Will this unlock my phone from its network carrier?
No. Flashing the stock firmware restores the phone’s original software, but it does not remove the SIM/network lock put in place by a carrier.
Q4. What is a .pac file?
A .pac file is a packed firmware file used for Spreadtrum/UNISOC chipsets. It contains all the necessary partitions—system, boot, recovery, modem, etc.—in a single, integrated file for flashing.
