Hi!
I yesterday bought a new wireless speaker. Checking the firmware version I figured it's quite dated and not supported anymore. Spotify and DLNA works well, but standard Internetradio doesn't, the app stinks. So I checked if theres a custom firmware, theres not. Now I found out I can telnet with user:admin pw:admin into the device 
The device comes with Linux kernel 2.6.xx and busybox installed (Commands available: arp, arping, ash, basename, cat, chmod, chpasswd, cp, date, df, du, echo, expr, find, free, grep, halt, hostname, ifconfig, init, init, insmod, kill, killall, ln, login, ls, lsmod, lzmacat, mdev, mkdir, mknod, mount, mv, nice, ping, ping6, pkill, poweroff, printf, ps, pwd, reboot, rm, rmmod, route, sed, sh, sleep, sync, tee, telnetd, test, tftpd, top, touch, udhcpc, umount, unlzma, uptime, vconfig, vi, wc, wget). The CPU is a MT7620 with I think a Ralink RT2860 wireless chip. It has 64MB RAM, not sure about the complete flash, "du -S /" shows me I guess 16MB. No Ethernet port unfortunately.
First question: How well do those chips work with OpenWRT? DO you think it will be hard to port OpenWRT to this device? I have very limtied experience with porting. Didnt disassemble the device till now, but I would try to locate a serial connection. Unfortunately there is no Ethernet port. Can you tell me how I can backup the firmware with the aforementioned tools over telnet? IS this even possible? Thanks!
Yes, generic SoC support is available but I doubt it's worth taking at stab at it with unless you really want to. You first need to locate serial and make sure it's working otherwise you'll most likely brick it and be unable to recover.
Audio support is available but you wont be able to recreate the same functionality since there's no port of a spotify client (to my knowledge) that works on mips and/or small storage (librespot uses rust). Bluetooth shouldn't be too hard and possibly mpd but that's about what you'll be able to run on that hardware.
If you're deadset on hacking a speaker this seems like a much better platform https://youtu.be/ZB413S8KDmo?t=232 however I'm not sure if there's a serial connection available and/or if the bootloader is locked.
Hi Roxxor91,
I'm working on porting OpenWrt to a similar device. So far I've managed to compile a 4.14 master snapshot, and run it from RAM, after having uploaded it via serial with kermit. Mine also does not have an ethernet port (but connectors for one onboard, i think). On my device PCB the serial port was labeled, and easy to solder to.
I guess I should open the device and have a look and solder the serial. Nice, didnt know I can run OpenWRT from RAM. That makes experimenting way safer. So I'll see what I'll get.
@diizzy
I will try to perform a teardown of the firmware when I get it extracted completely. Quite cumbersome on telnet. I already found the spotify libraries. I have to see How they are implemented. I will also check out the labeled "charging USB port" on the back. I hope it's a simple USB port, so I can (if needed) increase storage. MPD would be the big bonus I really want, DLNA also should not be a big issue. Spotify certainly needs to be figured out.