[Moto G7 Power Questions & Answers] Stilbium:
Thanks a lot! Though it did not help... maybe I did something wrong.

So first I looked at getvar:

fastboot getvar all
(bootloader) version: 0.5
(bootloader) version-bootloader: MBM-2.1-ocean_retail-16222030b3b-201001
(bootloader) product: ocean
(bootloader) board: ocean
(bootloader) secure: yes
(bootloader) hwrev: PVT1
(bootloader) radio: 1
(bootloader) storage-type: emmc
(bootloader) emmc: 32GB SAMSUNG GD6BMB RV=08 PV=01 FV=0000000000000001
(bootloader) ram: 3GB SAMSUNG LP3 DIE=8Gb M5=01 M6=06 M7=00 M8=5F
(bootloader) cpu: SDM632
(bootloader) serialno: ....................
(bootloader) cid: 0x0032
(bootloader) channelid: 0x8d
(bootloader) uid: A37CC9D800000000000000000000
(bootloader) securestate: flashing_unlocked
(bootloader) factory-modes: disabled
(bootloader) iswarrantyvoid: yes
(bootloader) max-download-size: 536870912
(bootloader) reason: Reboot mode set to fastboot
(bootloader) imei: ....................
(bootloader) imei2:
(bootloader) meid:
(bootloader) date: 07-08-2020
(bootloader) sku: XT1955-5
(bootloader) carrier_sku: XT1955-5
(bootloader) battid: SB18C28956
(bootloader) iccid:
(bootloader) cust_md5:
(bootloader) max-sparse-size: 268435456
(bootloader) current-time: "Thu Apr 29 15:45:40 UTC 2021"
(bootloader) ro.build.fingerprint[0]: motorola/ocean/ocean:10/QPOS30.85-
(bootloader) ro.build.fingerprint[1]: 23-3/dc622c:user/release-keys
(bootloader) poweroffalarm: 0
(bootloader) ro.build.version.full: <not found>
(bootloader) ro.build.version.qcom: LA.UM.8.6.2.r1-06600-89xx.0
(bootloader) version-baseband: M632_41.00.01.162R OCEAN_NA_CUST
(bootloader) kernel.version[0]: Linux version 4.9.206-perf+ (nobody@andr
(bootloader) kernel.version[1]: oid-build) (clang version 8.0.12 for And
(bootloader) kernel.version[2]: roid NDK) #1 SMP PREEMPT Thu Oct 1 00:21
(bootloader) kernel.version[3]: :27 CDT 2020
(bootloader) sbl1.git: MBM-2.1-ocean_retail-a30e356d6d-201001
(bootloader) rpm.git: MBM-2.1-ocean_retail-20f2cf34-201001
(bootloader) tz.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) devcfg.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) keymaster.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) cmnlib.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) cmnlib64.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) prov.git: MBM-2.1-ocean_retail-6814a8d41f-201001
(bootloader) aboot.git: MBM-2.1-ocean_retail-16222030b3b-201001
(bootloader) frp-state: no protection (0)
(bootloader) ro.carrier: retus
(bootloader) current-slot: b
(bootloader) running-boot-lun: 0
(bootloader) running-slot: _b
(bootloader) slot-suffixes: _a,_b
(bootloader) slot-count: 2
(bootloader) slot-successful:_a: Yes
(bootloader) slot-successful:_b: Yes
(bootloader) slot-bootable:_a: Yes
(bootloader) slot-bootable:_b: Yes
(bootloader) slot-retry-count:_a: 6
(bootloader) slot-retry-count:_b: 6
(bootloader) pcb-part-no: SP69A6P7PU
all: listed above
finished. total time: 0.014s

and noticed that the current-slot/running-slot is b.

Grabbed the latest retus Moto firmware from lolinet (the same 10/QPOS30.85) and then, as probably expected:

$ fastboot flash modem NON-HLOS.bin
target reported max download size of 536870912 bytes
sending 'modemb' (65428 KB)...
OKAY [ 2.616s]
writing 'modemb'...
(bootloader) Invalid partition name modemb
FAILED (remote failure)
finished. total time: 2.617s

Then:

$ fastboot flash modem_b NON-HLOS.bin
target reported max download size of 536870912 bytes
sending 'modem_b' (65428 KB)...
OKAY [ 2.612s]
writing 'modem_b'...
OKAY [ 1.110s]
finished. total time: 3.722s

$ fastboot erase modemst1
erasing 'modemst1'...
OKAY [ 0.017s]
finished. total time: 0.017s

$ fastboot erase modemst2
erasing 'modemst2'...
OKAY [ 0.017s]
finished. total time: 0.018s

$ fastboot flash fsg_b fsg.mbn
target reported max download size of 536870912 bytes
sending 'fsg_b' (9204 KB)...
OKAY [ 0.368s]
writing 'fsg_b'...
OKAY [ 0.121s]
finished. total time: 0.490s

After reboot everything is exactly the same as before - i.e. the same problems remained, no new ones showed up.

UPD: actually, no - the phone is reachable, it rings, but neither I can hear the other party, nor I am heard by anyone.

Maybe I had to flash both a and b slots?

Since my carrier is T-Mobile (though the phone is retail), would it make any sense to try to flash the radio from the T-mobile ROM? There are two ROMs available - RETUS (which I used) and TMO.

Looks like I'll have to temporarily go back to the stock... my fault anyway, needed to check more carefully what the LOS "official support" actually means :)

Thank you.