[Redmi Note 8 Questions & Answers] lueromat:
those commands completed without problem, and after the fh command the phone is disconnected in my device manager for a second, so it appears the xml command worked. however, when it reappears in device manager it's still on com40, and I cannot boot into bootloader. maybe a different command will do it? at least it's listening. here is the log:

C:\Program Files (x86)\Qualcomm\QPST\bin>QSaharaServer.exe -u 40 -s 13:"prog_emmc_firehose_Sm6125_ddr.elf"
Binary build date: Jun 25 2019 @ 03:16:15
QSAHARASERVER CALLED LIKE THIS: 'QSaharaServer.ex'Current working dir: C:\Program Files (x86)\Qualcomm\QPST\bin
Sahara mappings:
2: amss.mbn
6: apps.mbn
8: dsp1.mbn
10: dbl.mbn
11: osbl.mbn
12: dsp2.mbn
16: efs1.mbn
17: efs2.mbn
20: efs3.mbn
21: sbl1.mbn
22: sbl2.mbn
23: rpm.mbn
25: tz.mbn
28: dsp3.mbn
29: acdb.mbn
30: wdt.mbn
31: mba.mbn
13: prog_emmc_firehose_Sm6125_ddr.elf

18:15:01: Requested ID 13, file: "C:\Program Files (x86)\Qualcomm\QPST\bin\prog_emmc_firehose_Sm6125_ddr.elf"

18:15:01: 591740 bytes transferred in 0.125000 seconds (4.5146MBps)

18:15:01: File transferred successfully

18:15:01: Sahara protocol completed

C:\Program Files (x86)\Qualcomm\QPST\bin>fh_loader.exe --port=\\.\COM40 --sendxml=reboot.xml --showpercentagecomplete --zlpawarehost=1 --memoryname=emmc

Base Version: 19.06.10.18.44
Binary build date: Jun 25 2019 @ 03:16:10
Incremental Build version: 19.06.25.03.16.10

18:15:07: INFO: FH_LOADER WAS CALLED EXACTLY LIKE THIS
************************************************
fh_loader.exe --port=\\.\COM40 --sendxml=reboot.xml --showpercentagecomplete --zlpawarehost=1 --memoryname=emmc
************************************************

18:15:07: INFO: Current working dir (cwd): C:\Program Files (x86)\Qualcomm\QPST\bin\
18:15:07: INFO: Showing network mappings to allow debugging
18:15:07: INFO:

18:15:07: INFO: Trying to store 'reboot.xml' in string table
18:15:07: INFO: Looking for file 'reboot.xml'
18:15:07: INFO: User wants to talk to port '\\.\COM40'
18:15:07: INFO: Took 0.00000000 seconds to open port
18:15:07: INFO: Sorting TAGS to ensure order is <configure>,<erase>, others, <patch>,<power>
18:15:07: INFO: Sending <configure>

18:15:07: INFO: TARGET SAID: 'INFO: Binary build date: Jul 3 2019 @ 22:23:56'

18:15:07: INFO: TARGET SAID: 'INFO: Binary build date: Jul 3 2019 @ 22:23:56
'

18:15:07: INFO: TARGET SAID: 'INFO: Chip serial num: 570422912 (0x21fff680)'

18:15:07: INFO: TARGET SAID: 'INFO: Supported Functions (14):'

18:15:07: INFO: TARGET SAID: 'INFO: program'

18:15:07: INFO: TARGET SAID: 'INFO: read'

18:15:07: INFO: TARGET SAID: 'INFO: nop'

18:15:07: INFO: TARGET SAID: 'INFO: patch'

18:15:07: INFO: TARGET SAID: 'INFO: configure'

18:15:07: INFO: TARGET SAID: 'INFO: setbootablestoragedrive'

18:15:07: INFO: TARGET SAID: 'INFO: erase'

18:15:07: INFO: TARGET SAID: 'INFO: power'

18:15:07: INFO: TARGET SAID: 'INFO: firmwarewrite'

18:15:07: INFO: TARGET SAID: 'INFO: getstorageinfo'

18:15:07: INFO: TARGET SAID: 'INFO: benchmark'

18:15:07: INFO: TARGET SAID: 'INFO: emmc'

18:15:07: INFO: TARGET SAID: 'INFO: ufs'

18:15:07: INFO: TARGET SAID: 'INFO: fixgpt'

18:15:07: INFO: TARGET SAID: 'INFO: End of supported functions 14'

18:15:07: INFO: TARGET SAID: 'INFO: Calling handler for configure'

18:15:07: INFO: TARGET SAID: 'INFO: Storage type set to value eMMC'

18:15:07: INFO: TARGET SAID: 'WARN: NAK: MaxPayloadSizeToTargetInBytes sent by host 1048576 larger than supported 16384'
18:15:07: INFO: fh.attrs.MaxPayloadSizeToTargetInBytes = 16384
18:15:07: INFO: fh.attrs.MaxPayloadSizeToTargetInBytesSupported = 16384
18:15:07: INFO: Target returned NAK for your <configure> but it does not seem to be an error. This is ok, fh_loader.exe attributes updated

Send RESET to target with DelayInSeconds="2" ? (y|n):y

18:15:10: INFO: Sending <power>

18:15:10: INFO: TARGET SAID: 'INFO: Calling handler for power'
18:15:10: INFO: ==============================================================
18:15:10: INFO: Files used and their paths
18:15:10: INFO: 1 'C:\Program Files (x86)\Qualcomm\QPST\bin\port_trace.txt'
18:15:10: INFO: 2 'C:\Program Files (x86)\Qualcomm\QPST\bin\reboot.xml'

18:15:10: INFO: _ (done)
18:15:10: INFO: | |
18:15:10: INFO: __| | ___ _ __ ___
18:15:10: INFO: / _` |/ _ \| '_ \ / _ \
18:15:10: INFO: | (_| | (_) | | | | __/
18:15:10: INFO: \__,_|\___/|_| |_|\___|
18:15:10: INFO: {All Finished Successfully}

18:15:10: INFO: Overall to target 2.922 seconds (0.00 Bps)

Writing log to 'C:\Program Files (x86)\Qualcomm\QPST\bin\port_trace.txt', might take a minute

Log is 'C:\Program Files (x86)\Qualcomm\QPST\bin\port_trace.txt'