[HTC 10 Guides, News, & Discussion] nkk71:
The tool will also save you a couple minutes, and since you're only interested in firmware don't forget the -f flag ;)

I flashed yesterday, all went smoothly, here's my complete command prompt output (colour coded too :p, note the blue and red parts)

(i chose htc_fastboot, but normal fastboot will be fine too)

C:\ADB\ADB_10>[B][COLOR="Blue"]adb reboot download[/COLOR][/B]

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe getvar all[/COLOR][/B]
(bootloader) kernel: lk
(bootloader) product: htc_pmeuhl
(bootloader) version: 1.0
(bootloader) imei: 35xxxxxxxxxxxxx
(bootloader) version-main: 1.30.401.1
(bootloader) boot-mode: download
(bootloader) version-baseband: 1.0.U010013@60331.4
(bootloader) version-bootloader: 1.0.0.0000
(bootloader) mid: 2PS620000
(bootloader) cid: HTC__J15
all:
finished. total time: 0.006s
htc_fastboot finished. total time: 0.337s

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe oem rebootRUU[/COLOR][/B]
...
OKAY [ 0.155s]
finished. total time: 0.155s
htc_fastboot finished. total time: 0.331s

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe flash zip PMEUHL_1.80.401.1_NoWipe_TWRP3024_2.zip[/COLOR][/B]
htc_fastboot v3.0.9.2 (2015-05-29)
target reported max download size of 800000000 bytes
sending 'zip' (85571 KB)...
OKAY [ 4.581s]
writing 'zip'...
(bootloader) HOSD CL#738269
(bootloader) GPT is up-to-dated. [17408]
(bootloader) Perform pre-update
(bootloader) start@32
(bootloader) aboot_signed.img@100%
(bootloader) adsp.img@BYPASS
(bootloader) apdp-8996-1.img@BYPASS
(bootloader) cache.img@BYPASS
(bootloader) cmnlib32.img@100%
(bootloader) cmnlib64.img@100%
(bootloader) cota.img@BYPASS
(bootloader) cs_CY8C.img@BYPASS
(bootloader) devcfg-8996-1.img@100%
(bootloader) dsp.img@BYPASS
(bootloader) fsc.img@BYPASS
(bootloader) hosd_signed.img@100%
(bootloader) hyp-8996-1.img@100%
(bootloader) keymaster.img@100%
(bootloader) lksecapp.img@100%
(bootloader) modemst1.img@BYPASS
(bootloader) modemst2.img@BYPASS
(bootloader) pg2fs_ship_signkey.img@BYPASS
(bootloader) pmic-8996-1.img@100%
(bootloader) rcdata.img@BYPASS
(bootloader) recovery.img@BYPASS
(bootloader) rfg_3.img@BYPASS
(bootloader) rpm-8996-1.img@100%
(bootloader) sensor_hub.img@BYPASS
(bootloader) slpi.img@BYPASS
(bootloader) tp_SYN3708.img@BYPASS
(bootloader) tz-8996-1.img@100%
(bootloader) usb_typec.img@BYPASS
(bootloader) usb_typec_otp.img@BYPASS
(bootloader) venus.img@BYPASS
(bootloader) xbl-8996-1.img@100%
(bootloader) radio.img@BYPASS
[B][COLOR="Red"]FAILED (remote: 90 hboot pre-update! please flush image again immediately )[/COLOR][/B]
finished. total time: 6.153s
htc_fastboot finished. total time: 6.601s

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe flash zip PMEUHL_1.80.401.1_NoWipe_TWRP3024_2.zip[/COLOR][/B]
htc_fastboot v3.0.9.2 (2015-05-29)
target reported max download size of 800000000 bytes
sending 'zip' (85571 KB)...
OKAY [ 4.571s]
writing 'zip'...
(bootloader) HOSD CL#761759
(bootloader) GPT is up-to-dated. [17408]
(bootloader) start@32
(bootloader) aboot_signed.img@100%
(bootloader) adsp.img@100%
(bootloader) apdp-8996-1.img@100%
(bootloader) cache.img@100%
(bootloader) cmnlib32.img@100%
(bootloader) cmnlib64.img@100%
(bootloader) cota.img@100%
(bootloader) devcfg-8996-1.img@100%
(bootloader) dsp.img@100%
(bootloader) fsc.img@100%
(bootloader) cs_CY8C.img@BYPASS
(bootloader) hosd_signed.img@100%
(bootloader) hyp-8996-1.img@100%
(bootloader) keymaster.img@100%
(bootloader) lksecapp.img@100%
(bootloader) modemst1.img@100%
(bootloader) modemst2.img@100%
(bootloader) pg2fs_ship_signkey.img@100%
(bootloader) pmic-8996-1.img@100%
(bootloader) rcdata.img@100%
(bootloader) recovery.img@100%
(bootloader) rfg_3.img@100%
(bootloader) rpm-8996-1.img@100%
(bootloader) slpi.img@100%
(bootloader) tz-8996-1.img@100%
(bootloader) venus.img@100%
(bootloader) xbl-8996-1.img@100%
(bootloader) radio.img@100%
(bootloader) sensor_hub.img@0%
(bootloader) sensor_hub.img@0%
(bootloader) sensor_hub.img@0%
(bootloader) sensor_hub.img@20%
(bootloader) sensor_hub.img@40%
(bootloader) sensor_hub.img@55%
(bootloader) sensor_hub.img@80%
(bootloader) sensor_hub.img@100%
(bootloader) sensor_hub.img@100%
(bootloader) tp_SYN3708.img@BYPASS
(bootloader) usb_typec.img@BYPASS
(bootloader) usb_typec_otp.img@BYPASS
[B][COLOR="Green"](bootloader) Update zip file OK
(bootloader) end@Done
OKAY [ 51.153s]
finished. total time: 55.725s
htc_fastboot finished. total time: 55.977s[/COLOR][/B]

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe reboot-bootloader[/COLOR][/B]
htc_fastboot v3.0.9.2 (2015-05-29)
rebooting into bootloader...
OKAY [ 0.001s]
finished. total time: 0.001s
htc_fastboot finished. total time: 0.182s

[B][COLOR="Blue"]===> back to download mode using volume keys and power[/COLOR][/B]

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe getvar all[/COLOR][/B]
(bootloader) kernel: lk
(bootloader) product: htc_pmeuhl
(bootloader) version: 1.0
(bootloader) imei: 35xxxxxxxxxxxxx
(bootloader) version-main: 1.80.401.1
(bootloader) boot-mode: download
(bootloader) version-baseband: 1.0.U010013@60331.4
(bootloader) version-bootloader: 1.0.0.0000
(bootloader) mid: 2PS620000
(bootloader) cid: HTC__J15
all:
finished. total time: 0.006s
htc_fastboot finished. total time: 0.212s

C:\ADB\ADB_10>[B][COLOR="Blue"]htc_fastboot_3.0.9.2.exe reboot-bootloader[/COLOR][/B]
htc_fastboot v3.0.9.2 (2015-05-29)
rebooting into bootloader...
OKAY [ 0.001s]
finished. total time: 0.001s
htc_fastboot finished. total time: 0.184s