Help needed on flashing back K750i

Alright guys, i'm new here and i hope i post at the correct section. The case now is, i got an used set of K750i from my bro, and the phone were actually been flashed to W800i before. And now i would to flash it back to stock which is the original K750i. But i faced problem as below:

Quote:

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23:04:44| Baseband ID: 8040
23:04:44| Protocol Version: 3.1
23:04:44| Phone has restarted successfully...
23:04:44|
23:04:44| Profiling SEMC phone...
23:04:44| Platform: DB2010
23:04:44| OTP CID: 36
23:04:44| EROM CID: 36
23:04:44| EROM Color: Brown
23:04:44| IMEI: ------------------------
23:04:44| Phone ID: K750
23:04:44| Region: APAC_1
23:04:44| CDA: CDA102239/43 R15A
23:04:44| Firmware Version: R1BC002
23:04:44| EROM: n/a
23:04:44| Ready for operation!
23:05:11|
23:05:11| Sending db2010_cid49brown_flash_r5a.bin...
23:05:11| Prologue: Failed
23:05:11| Error: Cannot send flash loader
23:05:11| Error: Flashing failed
23:05:13| Disconnected... Unplug the phone

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May i know how am i going to solve this problem?

P/s: I had try on both:

K750_R1N005_FS_EMEA_6_BROWN36
K750_R1CA021_FS_EMEA_6_RED36

It seems like no go for me.