[MTCB Android Head Units Q&A] nook'r:
Here is my sys.txt file from 9.6.29.427562 kitkat edition. navigation working in the background.

you may need to edited to fit your unit.

[device]

type="android"

[android]

Fullscreen=1

tablet=1(0)

has_physical_home_button=1(0)

[gps]

location_gps=1

accuracy_workaround=1

background_navigation=1

[skin_arine]

back_to_screensaver = 10

skin_version = 0

hud_maneuvers_color =0

skin_new_year = 0

[rawdisplay]

screen_xy="auto"

[interface]

laneinfo_signpost_enabled=1

signposts_without_laneinfo=1

show_scroll_button=1

generated=2

offset_x=0

offset_y=0

capture_to_jpeg=1

[content]

delayed_resize=1

max_size_x=-1

max_size_y=-1

suppress_in_portrait_mode=0

[generated]

precise_lane_highlight=1

arrow_highlight_mode=3

add_decorations=1

[debug]

experimental_features=1

my_picture_POI=content\pictures\

raster_quality=0

screenshotsavecameraini=0

screenshotfilename="captures\ecran_%02d.jpg"

show_junction_view=1

show_signpost=1

sound_q_length=200

skip_eula=1

hnr=1

hnr_silent_startup=1

show_hnr=1

[route]

hnr_ignored_missing_country_ids=*

minimum_hnr_distance_km=100

[route.histspeed]

enabled=1

show=1

use_timeslice=1

[route.histspeed.timeslice]

day=1

hour=1

minute=1

[dynamiccompressor]

compressor=1

ratio=9

gain=9

[feature]

back_button=1

[folders]

linked_root_list="/storage/extSDCard/iGO /storage/sdcard2/iGO /sdcard2/iGO /sdcard/external_sd/iGO /ext_card/iGO /mnt/_ExternalSD/iGO /mnt/emmc/iGO /mnt/extern_sd/iGO /mnt/external_sd/iGO /mnt/exsdcard/iGO /mnt/ext_card/iGO /mnt/ext_sd/iGO /mnt/extsd/iGO /mnt/extSdCard/iGO /mnt/sdcard/_ExternalSD/iGO /mnt/sdcard/external_sd/iGO /mnt/sdcard/ExtStorages/iGO /mnt/sdcard/extStorages/SdCard/iGO /mnt/sdcard2/iGO /storage/sdcard1/iGO /storage/sdcard0/iGO /storage/iGO /sdcard/sd/iGO /mnt/sdcard-ext/iGO /mnt/sdcard/sd/iGO /mnt/sd/iGO /mnt/sdcard/iGO /mnt/iGO /sdcard/iGO /storage/sdcard1/iGO /mnt/sdcard1/iGO /mnt/ext/SdCard/iGO /storage/ext/SdCard/iGO /storage/emulated/0/iGO"

has_secondary_root=0

android_secondary_root_path="/storage/extSdCard/Addons"

content="/storage/extSdCard/Addons/content"

[network]

available=1

[http]

enabled=1

[tmc-http]

enabled=1

start=1

servers.size=3

servers[0].url="http://zippy.naviextras.com/services/tmclite/data/nng-igo-tmc-iphone/0/"

servers[2].url="http://zippy.naviextras.com/services/tmclite/data/nng-igo-tmc-becker/0/"

servers[1].url="http://zippy.naviextras.com/services/tmclite/data/nng-igo-tmc-russia/0/"

servers[2].url="http://tmchttp0.naviextras.com/nng-igo-tmc-primo/0/"

[naviextras]

boot_service_address="http://zippy.naviextras.com/services/index/rest/2/boot"

[services]

server_addr="https://android.naviextras.com/"

[google]

enabled=1

servers.size=1

servers[0].url="http://zippy.naviextras.com/services/tmclite/data/nng-igo-tmc-iphone/0/

start=1

[tmc]

internal_tmc_name="gnse"

port="/dev/gnstmc,0"

servers.size=1

servers[0].url="http://zippy.naviextras.com/services/tmclite/data/nng-igo-tmc-iphone/0/"

source="gnse"

start=1

[map]

show_signpost=1

[navigation]

autoreplan_action=AUTO

env_zone_warning_distance=500

junction_view_at_maneuver=1

junction_view_needs_signpost=0

junction_view_distance_highway=800 ;(800)

junction_view_distance_ramp=400 ;(400)

junction_view_distance=300 ;(300)

junction_view_on_highways_only=0

junction_view_type="mixed"

junction_view_blink_time=400

junction_view_blink_time_no_lane=400

show_city_in_next_street=1

show_city_in_next_street_distance=2000

track_simulation_speed=1

sim_speed_factor=2.5

[sound]

alert_volume=255

csv_voice_enabled=1

dev_channels=2

ding_muted=1

ding_volume=0

lua_voice_enabled=1

mute_os_key=1

pause_mp3_sooner=1

queue_length=200

wheelsound=0

working=1

[sound.announcer]

gps_signal_lost=0

gps_disconnected=0

[sound.speech]

delay_msec_between_speeches=0

[sound.voice]

drive_sentence_without_force=1

[traffic.settings]

traffic_enabled=1

[other]

asr_enabled=1 ; (habilita o VR -- Reconhecimento de Voz)

[vmc_voice]

enter_script=sc_volmanager_voice

vmc_effect=100

vmc_media=20

[vmc_vr]

vmc_voice=100

vmc_media=-1

vmc_alarmeffect=100

vmc_effect=0

[vr]

after_ding_delay=600

disabled=1 ; (0 habilita e 1 desabilita o VR)

ding_file_name="!msgbox"

microphone_early_delay=300 ; (microphone scratch)

open_microphone_early=1

timeout_trailing_silence_ovde=2000

use_low_conf_question=0

vde_accuracy=2000

[tts]

accusative_case=0

always_say_road_names=3

announce_exit_directions=3

announce_street_name=1

correction_overspeed_unit=1

priority=HIGH

skip_exit_numbers=1

supress_prepare_to=1

tts_buffer=524288

tts_gc_size=524288

tts_logics=3

ttspro_da_voice_enabled=1

use_tts_lang=1

[warning]

approach_beep_sound="!alert3"

approach_beep_spoken_type=1

is_spoken=1

max_section_time=40

mute_voice_announce_during_alert=0

overspeed_sound=0

overspeed_spoken_type=1

send_warn_event=1

speak_tts_only=0

speedcam_continuous_approach_beep_when_tonal=1

speedcam_enabled=1

speedcam_maxdistance_from_road=20

speedcam_max_angle=60

speedcam_max_lookahead=900

speedcam_soundtype=1

speedcam_soundtype_0=2

speedcam_soundtype_1=2

speedcam_soundtype_2=2

speedcam_soundtype_3=2

speedcam_soundtype_4=2

speedcam_soundtype_5=2

speedcam_soundtype_6=2

speedcam_soundtype_7=2

speedcam_soundtype_8=2

speedcam_soundtype_9=2

speedcam_soundtype_10=2

speedcam_soundtype_11=2

speedcam_soundtype_12=2

speedcam_soundtype_13=2

speedcam_soundtype_14=2

speedcam_soundtype_15=2

speedcam_soundtype_16=2

speedcam_soundtype_17=2

speedcam_soundtype_18=2

speedcam_soundtype_19=2

speedcam_soundtype_20=2

speedcam_soundtype_21=2

speedcam_soundtype_22=2

speedcam_soundtype_23=2

speedcam_soundtype_30=2

speedcam_soundtype_31=2

speedcam_visualtype=1

speedcam_warning=1

speedlimit_warning_visual=1

speedwarn_alt_tolerance=100

speedwarn_tolerance=100