Using the SPD Flash Tool R400001 is relatively straightforward. Here's a step-by-step guide to get you started:
SPD phones enter download mode very briefly. Unlike Qualcomm's EDL mode (which stays on), SPD’s BootROM (BROM) mode lasts only 2–3 seconds. If the flash tool doesn't send the download agent in that window, the phone boots normally and the tool throws error R400001 . spd flash tool r400001