LG Leon 4G LTE: phone start but launch a command-like mode

Hi,
I've got a LG Leon 4G LTE, 4 days ago the phone seems to have its batteries empty, but when I charged up my phone and turn it on, right after the LG logo it show me a black screen with some code on it.

Code:

---

[24650] fastboot_init()
[24650] Error: Auto CMD12 error
[24650] Error: Command timeout error
[24650] Failed to send stop command
[24660] Failed Readind block @ 1f78
[24660] Error: cannot read data
[24760] USB init ept @ 0x8f1df000
[24280] udc_start()

---

I tried to search internet and forums but I just found things similar but wich were not the came code / phone, and it was around two years old, also it did not seems that what I've found worked for anyone..
If someone could tell me what the problem is, why it does happens and if I can how can I solve it..
Thanks