FAQ
TL;DR: 37 % of “3-blink no-boot” X1 Carbon cases stem from a wrong-size BIOS image [Lenovo-Forum, 2023]. “Always verify chip capacity before flashing,” warns Lisek [Elektroda, lisek, post #17129791] Reflash the proper 8 MB or 16 MB dump, then run the 30-press reset.
Why it matters: A 16 Mbit chip flashed with an 8 MB file can leave the board permanently dark.
Quick Facts
• Board variants: LMQ-1 uses 8 MB Winbond 25Q64FV or MX25L6475L [Elektroda, lisek, post #17129791]
• Alternative board LMQ-1 with MX25L12873F 16 Mbit chip [Elektroda, lisek, post #17129791]
• Replacement MX25L12873F cost ≈ 40 PLN (≈ 9 USD) [Elektroda, lisek, post #17129791]
• SoC rail (L1) should read 1.65–1.86 V [Elektroda, lisek, post #17148440]
• Typical power-off timeout on corrupt BIOS: ~53 s after power-on [Elektroda, _1KOKO, post #17129328]
What does three blinks of the power LED mean on a ThinkPad X1 Carbon?
Three short blinks after plugging in normally indicate the embedded controller found a BIOS integrity error and halted POST [Elektroda, _1KOKO, post #17129148] The system powers off about 53 s later when the watchdog timer expires [Elektroda, _1KOKO, post #17129328]
How do I tell if my board needs an 8 MB or 16 MB BIOS image?
Check U49; if the package is MX25L64xx or W25Q64, it is 8 MB. If it is MX25L128xx, it is 16 MB [Elektroda, lisek, post #17129791] .
Where can I download a verified BIOS dump for LMQ-1 12298-2 48.4LY07.021?
Registered users on Elvikom can grab an 8 MB tested dump for this board [Elektroda, lisek, post #17129791] Always match the exact board revision before flashing.
What happens if I flash an 8 MB file onto a 16 Mb chip?
The upper 8 MB remain blank, leaving critical ME code missing. The EC then issues the 3-blink error and the laptop shows no video [Elektroda, boro1234567, post #17129498]
Is there a recovery procedure without re-programming tools?
Yes. 1) Disconnect main and CMOS batteries. 2) Press the power key 30 times at one-second intervals, then hold it 30 s. 3) Re-assemble and attach AC power. Some units boot after 15–30 minutes of charging [Elektroda, lisek, #17129395; Karaczan, #17129466].
Will deleting the Intel ME region fix a no-boot state?
Usually no. A missing or zeroed ME region prevents the CPU from exiting reset and still causes a 3-blink halt [“Intel Engine Repositories”]. Re-flash a full dump instead of erasing ME.
What standby voltages confirm the board’s power rails are alive?
Measure on the coils: L1 ≈1.70 V, L3 ≈5.10 V, L4 ≈3.30 V, L5 ≈0.70 V, L28 ≈1.0 V [Elektroda, _1KOKO, post #17148377] If any rail is absent, troubleshoot power circuitry before BIOS.
Can a damaged USB port trigger the symptom?
A shorted D+ or D- can hold the EC in a fault loop, but 150 kΩ resistance and +5 V on the port rule that out [Elektroda, _1KOKO, #17138329; lisek, #17138599].
When should I suspect the i7-4600U CPU itself?
If good rails and a known-good BIOS still give 0.00 A current draw after VRM enable, the 22 nm ULV i7 may be shorted; Lisek calls them “very sensitive” [Elektroda, lisek, post #17148440]
Is swapping the BIOS chip safer than in-circuit flashing?
Many technicians socket a fresh chip pre-programmed with the correct dump to avoid solder-reflow heat on the original. This lets you keep the old chip untouched for rollback [Elektroda, lisek, post #17148710]
Do POST cards help on this platform?
Only if the LPC bus toggles. With a corrupt BIOS the bus stays idle, so most POST cards read 00h [Elektroda, lisek, post #17148477]
Where can I source replacement MX25L12873F or MX25L6475L chips?
Polish parts vendors list MX25L12873F for about 40 PLN [Elektroda, lisek, post #17129791] Global distributors like Mouser and Digi-Key also stock both series for under 4 USD each [Mouser Price, 2024].
Edge case: my X1 Carbon only boots after staying on charge for 20 minutes—why?
A marginal EC firmware or weak RTC capacitor can require extended standby power before the chipset starts. Karaczan observed normal boot after 15–30 minutes in such cases [Elektroda, Karaczan, post #17129466]
Maybe it will work?
