Ensure you have the correct USB drivers installed if you are using a PC-based flashing tool.
This is the most comprehensive repository for this device. You can find sections for: skachat proshivku dlia huawei u8500
Downloading firmware for the Huawei U8500 (also known as the MTS Evo or Beeline E300) can be difficult because the device is very old. The most reliable resources are community forums where enthusiasts still archive files. Ensure you have the correct USB drivers installed
Ported MIUI builds for Android 2.3 Huawei U8500 - Прошивка MIUI (OS 2.3) . Installation Tips: as flashing will erase everything.
Charge the device to at least 50% and back up your data, as flashing will erase everything.