请问NI-nspire non-CAS with TouchPad意外升级到3.9如何降级？

dousha99

----[English version is avaliable on the bottom of this post]----

我的大黄(TI-nspire non-CAS with TouchPad, 16灰阶屏幕)被意外升级到了3.9, 同时boot2也被升级.
大黄序列号末位为B, USB-TTL是用Ardunio UNO改装的(短接RESET针脚和GND针脚即可，此时 另一个GND可用于接地，0用于RX, 1用于TX)
这是我已经尝试的事情：
问Google (度娘已经被自动跳过)尝试刷入ndless, 但是当连接USB后计算器重启, 安装失败 (无法打开nsnandmgr)
阅读这个帖子(http://www.cncalc.org/thread-6369-1-1.html)并尝试解决问题, 此时遇到了未预期的异常:
按下 doc + enter + B + ON 后出现空进度条和感叹号齿轮, 移除键盘和电池.
连接USB-TTL, 在超级终端中设置

1. 比特率 115200 kbps
   
2. 数据位 8
   
3. 奇偶校验 无
   
4. 停止位 1
   
5. 数据流控制 无

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在按照图示连接后 (25 - TX, 24 - RX, 23 - GND, 5 - GND, 从右向左数, 同电路板印刷时标号) 安装电池, 超级终端输出

1. Boot Loader Stage 1 (1.1.8916)
   
2. 
   
3. Build: 2007/4/23, 23:37:16
   
4. Copyright (c) 2006, 2007 Texas Instruments Incorporated
   
5. Using production keys
   
6. Last boot progress: 0
   
7. Clocks:  CPU = 90MHz   AHB = 45MHz   APB = 22MHz
   
8. 
   
9. Available system memory: 37292
   
10. Checking for NAND: NAND Flash ID: Samsung K9F5608Q0C
    
11. PM is turning the device OFF
    

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然后无响应. 我尝试将键盘装入并长按RESET超过15秒, 发现Boot2被重新刷入, 正常开机.
请问我遗漏了什么么？我可能还需要做些什么？ 谢谢指明！


----[听说论坛有外国大神，以下是英语翻译版]----

English is not my native language. I'm sorry if I made grammatical errors.
My TI-nspire non-CAS with TouchPad had been unexpectedly upgraded to version 3.9, and Boot2 had been updated too.
The last character of Serial Number is B, and USB-TTL cord is made from Ardunio UNO (by shorting RESET pin and GND pin. GND as GND, pin 0 as RX, pin 1 as TX)
These are what I've tried:
Google it.
Try to flash ndless. But it doesn't work as I connected calculator to computer, it restarts immediatly, then fails. (I can't use nsNandMgr due to this)
Read this post (http://www.cncalc.org/thread-6369-1-1.html) and try to solve it on my own, then I encounted an unexpected exception:
Press doc + enter + B + ON to delete Boot2. The screen shows an empty progress bar and a cog icon with a warning mark. Then I removed the keyboard and batteries
Connect USB-TTL cord, set up HyperTerminal as the setting below:

1. Bit rate 115200 kbps
   
2. Data bit 8
   
3. Parity None
   
4. Stop bit 1
   
5. Stream Control None

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I followed the instruction to connect calculator (25 - TX, 24 - RX, 23 and 5 - GND, from right to left as the marks on PCB), install batteries, then HyperTerminal read

1. Boot Loader Stage 1 (1.1.8916)
   
2. 
   
3. Build: 2007/4/23, 23:37:16
   
4. Copyright (c) 2006, 2007 Texas Instruments Incorporated
   
5. Using production keys
   
6. Last boot progress: 0
   
7. Clocks:  CPU = 90MHz   AHB = 45MHz   APB = 22MHz
   
8. 
   
9. Available system memory: 37292
   
10. Checking for NAND: NAND Flash ID: Samsung K9F5608Q0C
    
11. PM is turning the device OFF
    

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After that it goes unresponsive. I tried to plug keypad in and push RESET button for 15s. Boot2 had been reflashed and calculator started up normally as long as I released RESET button.
So, did I missed anything? What should I check in addition? Thanks in advance!