Try the following in case it is a corrupted BIOS that is causing the problem.
* Disconnect the charger (if connected) and remove the ''main battery'' from the laptop
* Next open the laptop and disconnect and remove the ''reserve battery'' from the motherboard. Here's the [link|https://dl.dell.com/manuals/all-products/esuprt_laptop/esuprt_latitude_laptop/latitude-c640_service%20manual_en-us.pdf|service manual] for the laptop. Go to p.36 of 53 (pdf page numbering) to view the ''necessary Notices and the pre-requisite steps and then the procedure'' to disconnect the battery. ''Note:'' If you have a DMM (digital multimeter) measure the reserve battery voltage once you have disconnected and removed it from the laptop. It is a 7.2V DC Rechargeable NiMH battery. If the battery has failed or measured <6.0V DC replace it. Search online for ''6P466 battery'' to get results for suppliers that suit you best
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* ''Press and hold the laptop's Power On button for a full 30 seconds and then release it''
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* ''Press and hold the laptop's Power On button for a full 30 seconds and then release it.'' Doing this will cause the BIOS settings to restore back to their factory default settings.
* Reconnect the reserve battery to the motherboard and reassemble the laptop
* Reinsert the main battery and connect the charger and try starting the laptop.
Try the following in case it is a corrupted BIOS that is causing the problem.
* Disconnect the charger (if connected) and remove the ''main battery'' from the laptop
-
* Next open the laptop and disconnect and remove the ''reserve battery'' from the motherboard. Here's the ][https://dl.dell.com/manuals/all-products/esuprt_laptop/esuprt_latitude_laptop/latitude-c640_service%20manual_en-us.pdf|service manual] for the laptop. Go to p.36 of 53 (pdf page numbering) to view the ''necessary Notices and the pre-requisite steps and then the procedure'' to disconnect the battery. ''Note:'' If you have a DMM (digital multimeter) measure the reserve battery voltage once you have disconnected and removed it from the laptop. It is a 7.2V DC Rechargeable NiMH battery. If the battery has failed or measured <6.0V DC replace it. Search online for ''6P466 battery'' to get results for suppliers that suit you best
+
* Next open the laptop and disconnect and remove the ''reserve battery'' from the motherboard. Here's the [link|https://dl.dell.com/manuals/all-products/esuprt_laptop/esuprt_latitude_laptop/latitude-c640_service%20manual_en-us.pdf|service manual] for the laptop. Go to p.36 of 53 (pdf page numbering) to view the ''necessary Notices and the pre-requisite steps and then the procedure'' to disconnect the battery. ''Note:'' If you have a DMM (digital multimeter) measure the reserve battery voltage once you have disconnected and removed it from the laptop. It is a 7.2V DC Rechargeable NiMH battery. If the battery has failed or measured <6.0V DC replace it. Search online for ''6P466 battery'' to get results for suppliers that suit you best
* ''Press and hold the laptop's Power On button for a full 30 seconds and then release it''
* Reconnect the reserve battery to the motherboard and reassemble the laptop
* Reinsert the main battery and connect the charger and try starting the laptop.
Hi,
Try the following in case it is a corrupted BIOS that is causing the problem.
* Disconnect the charger (if connected) and remove the ''main battery'' from the laptop
* Next open the laptop and disconnect and remove the ''reserve battery'' from the motherboard. Here's the ][https://dl.dell.com/manuals/all-products/esuprt_laptop/esuprt_latitude_laptop/latitude-c640_service%20manual_en-us.pdf|service manual] for the laptop. Go to p.36 of 53 (pdf page numbering) to view the ''necessary Notices and the pre-requisite steps and then the procedure'' to disconnect the battery. ''Note:'' If you have a DMM (digital multimeter) measure the reserve battery voltage once you have disconnected and removed it from the laptop. It is a 7.2V DC Rechargeable NiMH battery. If the battery has failed or measured <6.0V DC replace it. Search online for ''6P466 battery'' to get results for suppliers that suit you best
* ''Press and hold the laptop's Power On button for a full 30 seconds and then release it''
* Reconnect the reserve battery to the motherboard and reassemble the laptop
* Reinsert the main battery and connect the charger and try starting the laptop.