Power off the phone, disconnect and reconnect the battery(if possible) and connect USB cable...
Using Port:
AUTH info: MTK, version: 1
Boot META MODE...
Hold the VOL UP to force MediaTek BootROM.
Scanning BootROM or Preloader port... Done.
Detected MediaTek USB Port_V1632 (COM27)
Connection status: XHCI:HUB3:USB 2.0 High-Speed
USB Driver: [MediaTek Inc.] wdm_usb, version: 3.0.1504.0, date: 1-22-2015
Boot META MODE from BootROM ... Done.
Scanning META port... Done.
META port detected: MediaTek PreLoader USB VCOM_V1632 (Android) (COM71)
Boot META MODE successfully.
Modem info:
BaseBand chip: MT6750
SW time: 2000.00.00
DSP firmware version: 1.0
DSP patch version: MOLY.LR11.W1539.MD.MP.V20.3.P45
SW version: OPPO6755_66_D57_L_HW
HW version: Unknown
Melody version: LWCTG_50
AP info:
Platform: MT6750,S01
Build version: A1601EX_11_A.33_170814
SW version: A1601EX_11_A.33_170814
SW time: Mon Aug 14 23:17:42 CST 2017
HW version: S01
Writing imei...
imei[1]: 861117032....
imei[2]: 861117032....
IMEI written successfully.
Writing Wifi Mac (00:00:5e:5a:0c:87)... Done.